Metal compositions, thermal imaging donors and patterned multilayer compositions derived therefrom

ABSTRACT

The invention provides metal compositions, including silver compositions, and thermal imaging donors prepared with the compositions. The donors are useful for thermal transfer patterning of a metal layers and optionally, a corresponding proximate portion of an additional transfer layer onto a thermal imaging receiver. The compositions are useful for dry fabrication of electronic devices. Also provided are patterned multilayer compositions comprising one or more base film(s), and one or more patterned metal layers, including EMI shields and touchpad sensors.

This invention was made with United States Government support underAgreement No. 70NANB2H03032 awarded by NIST Advanced Technology Program.The United States Government has certain rights in the invention.

FIELD OF THE INVENTION

The invention relates to metal/polymer compositions and thermal imagingdonors for printing electronic circuits.

BACKGROUND

Thermal transfer processes are well known in applications such as colorproofing as a means of dry transferring or printing of dye and/orpigment layers. Such thermal transfer processes typically use a laser toinduce the image-wise thermal transfer of material.

Laser-induced thermal transfer processes typically use a donor element,including a layer of material to be transferred, referred to herein as atransfer layer, and a receiver element, including a surface forreceiving the transferred material. Either the substrate of the donorelement or the receiver element is transparent, or both are transparent.The donor element and receiver element are brought into close proximityor into contact with each other and selectively exposed to laserradiation, usually by an infrared laser. Heat is generated in theexposed portions of the transfer layer, causing the transfer of thoseportions of the transfer layer onto the surface of the receiver element.If the material of the transfer layer does not absorb the incoming laserradiation, the donor element should include a heating layer, also knownas a light-to-heat conversion (LTHC) layer or a transfer-assist layer,in addition to the transfer layer.

In a typical laser-induced digital thermal transfer process the exposuretakes place only in a small, selected region of the assembly at a time,so that transfer of material from the donor element to the receiverelement can be built up one region at a time. The region may be a pixel,some portion of a pixel or a plurality of pixels. Computer controlfacilitates the transfer at high speed and high resolution.Alternatively, in an analog process, the entire assembly is irradiatedand a mask is used to selectively expose desired portions of thethermally imageable layer.

There are several known examples of thermal transfer of layers for theconstruction of electronic devices. Representatives are U.S. Pat. No.6,114,088 and WO 2004/087434.

There is a need for thermal imaging donors that allow patterned thermaltransfer of conducting metal layers that exhibit good transferproperties and good adhesion to a variety of receivers. Particularlydesirable are thermal imaging donors wherein, after transfer, no furtherheating, or firing, of the patterned layer is required to achieve a highconductivity metal layer.

SUMMARY OF INVENTION

One aspect of the invention is a metal composition (A) comprising: (a)about 65 to about 95 wt %, based on the total weight of the metalcomposition, of a metal powder selected from the group: Ag, Cu andalloys thereof; comprising a plurality of metal particles having anaverage longest dimension of about 5 nm to about 1500 nm; and (b) about5 to about 35 wt % of a dispersant comprising one or more resinsselected from the group: conducting polymers selected from the group:polyaniline, polythiophene, polypyrrole, polyheteroaromatic vinylenes,and their derivatives; and nonconducting polymers selected from thegroup: acrylic and styrenic-acrylic latexes, and solution-based acrylicsand styrenic-acrylic (co)polymers, and combinations thereof; copolymersof ethylene with one or more monomers selected from the group:(meth)acrylate(s), vinyl acetate, carbon monoxide and (meth)acrylicacid; polyvinylacetate and its copolymers.

Another aspect of the invention is a multilayer thermal imaging donorcomprising: a base film and a metal transfer layer, wherein said metaltransfer layer comprises the metal composition (A).

Another aspect of the invention is a patterned multilayer compositioncomprising: (a) one or more base film(s); and (b) one or more patternedmetal layer(s);

wherein the patterned metal layer(s) has at least one line-width ofabout 1 millimeter or less, and comprises the metal composition (A).

The compositions and donors provide thermal transfer patterning of metallayers onto thermal transfer receivers. The patterned metal layersrequire no post-firing or annealing to induce the conductivity requiredfor electronic circuitry. The thermal imaging process is dry and hencedoes not involve solvent incompatibility issues with any layers, whichmay already have been deposited.

BRIEF DESCRIPTION OF FIGURES

FIG. 1A is a cross-sectional view of a thermal imaging donor 100comprising a metal transfer layer 106 and a base film 102.

FIG. 1B is a cross-sectional view of thermal imaging donor 100comprising a LTHC layer 108.

FIG. 2A is a cross-sectional view of a thermal imaging donor 100comprising an additional transfer layer 104.

FIG. 2B is a cross-sectional view of a thermal imaging donor 100comprising a LTHC layer 108 interposed between base film 102 and anadditional transfer layer 104.

FIGS. 3A, 3B and 3C are cross-sectional views of a thermal imaging donor100 comprising an additional transfer layer 110 on top of the metaltransfer layer 106.

FIG. 4 is a cross-sectional view of a thermal imaging receiver 200comprising a receiver base film 202 and optional adhesive layer 204.

FIGS. 5A and 5B are cross-sectional views of a patterned multilayercomposition.

FIGS. 6A and 6B are cross-sectional views of a patterned multilayercomposition comprising an additional transfer layer.

FIG. 7 is a cross-sectional view of a thermal imaging receiver 200comprising a base film 202 and at least one patterned layer 205.

FIGS. 8 & 9 illustrate scanning electron micrographs at 4,000×magnification of patterned multilayer compositions of one embodiment ofthe invention.

FIG. 10 illustrates the EMI shielding performance of a patternedmultilayer composition of one embodiment of the invention.

FIG. 11 is a photomicrograph at 5× magnification of an EMI shield of oneembodiment of the invention.

DETAILED DESCRIPTION

Herein the terms “acrylic”, “acrylic resin”, “(meth)acrylic resins”, and“acrylic polymers”, are synonymous unless specifically definedotherwise. These terms refer to the general class of addition polymersderived from the conventional polymerization of ethylenicallyunsaturated monomers derived from methacrylic and acrylic acids andalkyl and substituted-alkyl esters thereof. The terms encompasshomopolymers and copolymers. The terms encompass specifically thehomopolymers and copolymers of methyl (meth )acrylate, ethyl(meth)acrylate, butyl (meth )acrylate, 2-hydroxyethyl (meth)acrylate,(meth)acrylic acid and glycidyl (meth)acrylate. The term copolymerherein encompasses polymers derived from polymerization of two or moremonomers, unless specifically defined otherwise. The term (meth)acrylicacid encompasses both methacrylic acid and acrylic acid. The term(meth)acrylate, encompasses methacrylate and acrylate.

The terms “styrene acrylic polymers”, “acrylic styrene” and “styreneacrylic” are synonymous and encompass copolymers of the above described“acrylic resins” with styrene and substituted styrene monomers, forinstance alpha-methyl styrene.

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having” or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a process,method, article, or apparatus that comprises a list of elements is notnecessarily limited to only those elements but may include otherelements not expressly listed or inherent to such process, method,article, or apparatus. Further, unless expressly stated to the contrary,“or” refers to an inclusive or and not to an exclusive or. For example,a condition A or B is satisfied by any one of the following: A is true(or present) and B is false (or not present), A is false (or notpresent) and B is true (or present), and both A and B is true (orpresent).

Also, use of “a” or “an” are employed to describe elements andcomponents described herein. This is done merely for convenience and togive a general sense of the scope of the invention. This descriptionshould be read to include one or at least one and the singular alsoincludes the plural unless it is obvious that it is meant otherwise.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing of embodiments of the present invention, suitablemethods and materials are described below. All publications, patentapplications, patents, and other references mentioned herein areincorporated by reference in their entirety, unless a particular passageis cited. In case of conflict, the present specification, includingdefinitions, will control. In addition, the materials, methods, andexamples are illustrative only and not intended to be limiting.

To the extent not described herein, many details regarding specificmaterials, processing acts, and circuits are conventional and may befound in textbooks and other sources within the organic light-emittingdiode display, photodetector, photovoltaic, and semiconductive memberarts.

Metal Composition

One embodiment of the invention is a metal composition (A) comprising:(a) about 65 to about 95 wt %, based on the total weight of the metalcomposition, of a metal powder selected from the group consisting of:Ag, Cu and alloys thereof; comprising a plurality of metal particleshaving an average longest dimension of about 5 nm to about 1500 nm; and(b) about 5 to about 35 wt % of a dispersant comprising one or moreresins selected from the group consisting of: conducting polymersselected from the group consisting of: polyaniline, polythiophene,polypyrrole, polyheteroaromatic vinylenes, and their derivatives; andnonconducting polymers selected from the group consisting of: acrylicand styrenic-acrylic latexes, and solution-based acrylics andstyrenic-acrylic (co)polymers, and combinations thereof; copolymers ofethylene with one or more monomers selected from the group consistingof: (meth)acrylate(s), vinyl acetate, carbon monoxide and (meth)acrylicacid; polyvinylacetate and its copolymers.

Preferably the metal composition (A) comprises about 85 to about 90%metal powder with an average particle size of between 100 nm and about400 nm. In one preferred embodiment the metal powder is silver metalflake, with an average equivalent spherical diameter of about 100 toabout 900 nm. In various aspects of the invention the metal composition(A) comprises 96 wt % or greater, and preferably 98 wt % or greater, ofcomponents (a) and (b) as stated above. In another aspect the metalcomposition (A) consists essentially of the components (a) and (b) asstated above.

The metal composition (A) of the invention, relative to conventionalcompositions, has high loadings of metal particles. The composition isuseful in preparing metal transfer layers. The metal composition (A) isunique in that it provides a conducting layer after thermal transfer,without the need for firing or burning-off of polymer binders.

Silver is a preferred metal powder for the compositions. Preferredalloys include Ag—Pd, Ag—Pt and Ag—Cu. The metal powders are readilyavailable from several commercial sources including: Ferro Corp.,Electronic Materials Systems, South Plainfield, N.J.; Nanostructured &Amorphous Materials, Houston, Tex.; Inframat® Advanced Materials,Farmington, Conn.; Sumitomo Metal Mining Co., Ltd., Tokyo, Japan; andMitsui Mining and Smelting Co., Ltd. Tokyo, Japan.

“Dispersant” refers to non-volatile organic or inorganic material thatis used as a carrier or matrix medium for the metal particles. Thedispersant includes one or more of the following components: polymers,oligomers, surface treatments, plasticizers, processing aids such asdefoamers, surfactants, stabilizers, coating aids, pigments, dyesincluding near infrared dyes, and the like. The dispersant has severalfunctions including: allowing the dispersion of the metal particles sothey are evenly distributed and applied as transfer layers; andcontributing to the transfer properties, most notably the relativeadhesion of the metal transfer layers to the donor element and thethermal imaging receiver in the thermal transfer process. The dispersantalso may contribute to the functional properties of the transfer layers.For instance, the dispersant may be a conducting polymer.

The properties of the dispersant refer to the bulk properties of thefully formulated dispersant formulations, unless specifically noted.Preferred dispersants are polymers having a Tg of about −30° C. to about90° C., and more preferably, about 30° C. to about 70° C.

Polymers useful as dispersants in the invention include conductingorganic polymers and doped versions of these polymers, e.g.,polyaniline, polythiophene, polypyrrole, polyheteroaromatic vinylene,polyfuran, poly(para-phenylene), poly(phenylenevinylene),polyisothianaphthene, polyparaphenylene sulphide, and their derivatives.Preferred derivatives fall in one or more of the following categories:(a) stable conducting polymers such as polyaniline (PANI) andpolyethylene dioxythiophene (PEDOT); (b) soluble or dispersibleconducting polymers that form films using standard coating techniques,including PANI, PEDOT; and other alkyl- or alkoxy-substitutedderivatives of conducting polymers such as poly(2,5dialkoxy)paraphenylene vinylene and poly(3-hexyl)thiophene); and (c)conducting polymers that give high conductivity upon doping. Preferredconducting polymers are selected from the group consisting of:polyaniline; polythiophene; polypyrrole; polyheteroaromatic vinylenes;and their derivatives; preferably at a level of 1 to about 5 wt % basedon the dry weight of the metal transfer layer composition.

Further polymers useful as dispersants are those selected from the groupconsisting of: acrylic and styrenic-acrylic latexes and solution-basedacrylic and styrenic-acrylic (co)polymers including random and graftcopolymers; and combinations thereof; copolymers of ethylene with one ormore monomers selected from the group consisting of: (meth)acrylates,vinyl acetate, carbon monoxide and (meth)acrylic acid; polyvinylacetateand its copolymers; and polyvinylpyrrolidone and its copolymersincluding polyvinylpyrrolidone-co-vinyl acetate. Preferably thesolvent-soluble polymers within the group are characterized by an M_(w)of about 10,000 to about 200,000. A preferred dispersant comprisesresins selected from the group consisting of: acrylic andstyrenic-acrylic latexes, and solution-based acrylics andstyrenic-acrylic (co)polymers, and combinations thereof.

The dispersant may comprise up to about 10 wt % of one or more resinadditives selected from the group of consisting of: pigments, dyes andconducting particles selected from the group consisting of: carbonblack, carbon nanotubes, and modifying metal and metal alloy powders.Preferred modifying metals are Au and Pd. A preferred compositioncomprises 0.5 wt % to about 10 wt % of the conducting additive with anaverage particle size greater than 5 nm and less than about 1500 nm. Themost preferred conducting additives are carbon black and carbonnanotubes. Preferably the metal composition (A) further consistsessentially of 0.5 wt % to about 10 wt % of the conducting additive withan average particle size greater than 5 nm and less than about 1500 nm.In another embodiment preferred additives are near-infrared dyes andmore preferably, are cyanine compounds selected from the group:indocyanines, phthalocyanines including polysubstituted phthalocyaninesand metal-containing phthalocyanines, and merocyanines.

Lower molecular weight oligomers and small molecules useful asprocessing aids in the dispersant include surfactants, for instance,those comprising siloxy-, fluoryl-, alkyl- and alkynyl-substitutedsurfactants. These include the Byk® (Byk Chemie), Zonyl® (DuPont),Triton® (Dow), Surfynol® (Air Products) and Dynol® (Air Products)surfactants. Preferred are Byk® 345, 346 and 348 and Zonyl® FSO and FSNsurfactants.

The metal composition (A) is typically prepared by mixing metal powderand the dispersant with a volatile carrier fluid to provide a fluiddispersion. Typically the volatile carrier fluid is water, an organicsolvent, a gaseous material, or some combination thereof. The volatilecarrier fluid is chosen to be compatible with the metal particles andany optional dispersant that is used. Examples of volatile carrierfluids include water, lower alcohols such as ethanol, aliphatic andaromatic hydrocarbons such as hexane, cyclohexane and xylenes; etherssuch as dibutyl ether; ether alcohols such as 2-methoxyethanol; esterssuch as butyl acetate; and aliphatic and aromatic halocarbons such as1,2-dichloroethane.

Multilayer Thermal Imaging Donor

Another embodiment of the invention is a multilayer thermal imagingdonor. In various embodiments the donor comprises, in layered sequence,a base film, and optional LTHC layer, a metal transfer layer and anoptional protective strippable cover layer. The metal transfer layercomprises the metal composition (A) as described above. In oneembodiment the metal transfer layer consists essentially of the metalcomposition (A) as described above. Other embodiments can include one ormore additional transfer layers interposed between the base film and themetal transfer layer and/or on top of the metal transfer layer. Thus,one or more other conventional thermal transfer donor element layers canbe included in the thermal imaging substrate useful in the presentinvention, including but not limited to an interlayer, primer layer,release layer, ejection layer, thermal insulating layer, underlayer,adhesive layer, humectant layer, and light attenuating layer.

FIG. 1A is a cross-sectional view of thermal imaging donor 100, inaccordance with one embodiment of the invention. Thermal imaging donor100 comprises a base film 102 and a metal transfer layer 106 comprisinga novel metal composition dispersed on the surface of the base film.

Base film 102 provides support to the other layers of thermal imagingdonor 100. Base film 102 comprises a flexible polymer film that ispreferably transparent and remains stable despite heating of the LTHC orother layers. A suitable thickness for base film 102 is about 25 μm toabout 200 μm, although thicker or thinner support layers may be used.The base film may be stretched by standard processes known in the artfor producing oriented films and one or more other layers, such as theLTHC layer, may be coated onto the base film prior to completion of thestretching process. Preferred base films for thermal imaging donorscomprise a polymeric material selected from the group consisting of:polyethylene terephthalate (PET), polyethylene naphthalate (PEN),triacetyl cellulose and polyimide.

Light-Attenuating Agent

A light-attenuating agent may be present in a discrete layer orincorporated in one of the other functional layers of the donor element,such as the base film, the LTHC layer or in an additional transferlayer. In one embodiment, the base film comprises a small amount(typically 0.2% to 0.5% by weight of the base film) of alight-attenuating agent such as a dye which can assist in the focusingof the radiation source onto the radiation-absorber in the LTHC layerduring the thermal imaging step, thereby improving the efficiency of theheat transfer. U.S. Pat. No. 6,645,681, incorporated herein byreference, describes this and other ways in which the base film may bemodified to assist in the focusing of a laser radiation source in whichthe equipment comprises an imaging laser and a non-imaging laser whereinthe non-imaging laser has a light detector that is in communication withthe imaging laser. Herein, the light attenuating agent preferablyabsorbs or diffuses light in the visible region, and in one embodimentabsorbs around 670 nm. Suitable light-attenuating agents are well knownin the art and include the commercially available Disperse Blue 60 andSolvent Green 28 dyes and carbon black. Preferably the amount oflight-attenuating agent is sufficient to achieve an optical density (OD)of 0.1 or greater at some wavelength of about 400 to about 750 nm, andmore preferably about 0.3 to about 1.5.

Light to Heat Conversion Layer (LTHC)

The thermal imaging donor may, optionally, have alight-to-heat-conversion layer (LTHC), interposed between the base filmand the other layers. FIG. 1B is a cross-sectional view of thermalimaging donor 100, in accordance with another embodiment of theinvention. Thermal imaging donor 100 comprises a LTHC layer 108interposed between base film 102 and the metal transfer layer 106.

The LTHC layer 108 is incorporated as a part of thermal imaging donor100 for radiation-induced thermal transfer to couple the energy of lightradiated from a light-emitting source into the thermal transfer donor.

Typically, the radiation absorber in the LTHC layer (or other layers)absorbs light in the infrared, visible, and/or ultraviolet regions ofthe electromagnetic spectrum and converts the absorbed light into heat.The radiation absorber is typically highly absorptive, providing anoptical density (OD) at the wavelength of the imaging radiation of 0.1to 3 or higher, and preferably from 0.2 to 2.

Suitable radiation absorbing materials can include, for example, dyes(e.g., visible dyes, ultraviolet dyes, infrared dyes, fluorescent dyes,and radiation-polarizing dyes), pigments, metals, metal compounds, metalfilms, and other suitable absorbing materials. Suitable radiationabsorbers and binders for LTHC layers are well-known in the art andextensive lists and references can be found in PCT/US05/38010;PCT/US05/38009; U.S. Pat. No. 6,228,555 B1; Matsuoka, M., “InfraredAbsorbing Materials”, Plenum Press, New York, 1990; and Matsuoka, M.,Absorption Spectra of Dyes for Diode Lasers, Bunshin Publishing Co.,Tokyo, 1990; which are herein incorporated by reference. One example ofa suitable LTHC layer can include a pigment, such as carbon black, and abinder, such as an organic polymer. A preferred class of near-infrareddyes are cyanine compounds selected from the group: indocyanines,phthalocyanines including polysubstituted phthalocyanines andmetal-containing phthalocyanines, and merocyanines.

Sources of suitable infrared-absorbing dyes include H. W. SandsCorporation (Jupiter, Fla., US), American Cyanamid Co. (Wayne, N.J.),Cytec Industries (West Paterson, N.J.), Glendale ProtectiveTechnologies, Inc. (Lakeland, Fla.) and Hampford Research Inc.(Stratford, Conn.). Preferred dyes for LTHC and transfer layers are3H-indolium,2-[2-[2-chloro-3-[(1,3-dihydro-1,3,3-trimethyl-2H-indol-2-ylidene)ethylidene]-1-cyclopenten-1-yl]ethenyl]-1,3,3-trimethyl-,salt with trifluoromethanesulfonic acid (1:1) having CAS No.[128433-68-1] and molecular weight of about 619 grams per mole,available from Hampford Research Inc, Stratford, Conn., as TIC-5c;2-(2-(2-chloro-3-(2-(1,3-dihydro-1,1-dimethyl-3-(4-sulphobutyl)-2H-benz[e]indol-2-ylidene)ethylidene)-1-cyclohexene-1-yl)ethenyl)-1,1-dimethyl-3-(4-sulphobutyl)-1H-benz[e]indolium,inner salt, free acid having CAS No. [162411-28-1], available from H. W.Sands Corp, as SDA 4927; and indolenine dyes SDA 2860 and SDA 4733 fromH. W. Sands Corp. SDA 4927 is an especially preferred dye for the LTHClayer.

An LTHC layer may include a particulate radiation absorber in a binder.Examples of suitable pigments include carbon black and graphite.

The weight percent of the radiation absorber in the LTHC layer,excluding the solvent in the calculation of weight percent, is generallyfrom 1 wt % to 85 wt %, preferably from 3 wt % to 60 wt %, and mostpreferably from 5 wt % to 40 wt %, depending on the particular radiationabsorber(s) and binder(s) used in the LTHC layer. Suitable binders foruse in the LTHC layer include film-forming polymers, such as, forexample, phenolic resins (e.g., novolak and resole resins), polyvinylbutyral resins, polyvinyl acetates, polyvinyl acetals, polyvinylidenechlorides, polyacrylates, and styrene acrylics. The % transmittance ofthe LTHC layer is affected by the identity and amount of the radiationabsorber, and the thickness of the LTHC layer. The LTHC layer shouldexhibit radiation transmission of about 20% to about 80%, morepreferably of about 40% to about 50%, at the wavelength of the imagingradiation used in the thermal transfer imaging process. When a binder ispresent, the weight ratio of radiation absorber to binder is about 5:1to about 1:1000 by weight, preferably about 2:1 to about 1:100 byweight. A polymeric or organic LTHC layer is coated to a thickness of0.05 m to 20 m, preferably, 0.05 m to 10 m, and, more preferably, 0.1 mto 5 m.

In preferred embodiments of this invention, the LTHC layer is based upona broad variety of water-soluble or water-dispersible polymeric binderswith compositions as disclosed in the above referenced PCT/US05/38010and PCT/US05/38009. Preferably, the average particle size of awater-dispersible binder in its aqueous phase is less than 0.1 micron,and more preferably less than 0.05 micron, and preferably having anarrow particle size distribution. Preferred water-soluble orwater-dispersible polymeric binders for LTHC layers useful in theinvention are those selected from the group: acrylic resins, andhydrophilic polyesters and more preferably from sulphonated polyestersas described in the above referenced PCT/US05/38009.

Other preferred polymeric binders for LTHC layers are maleic anhydridehomopolymers and copolymers including those comprising functionalityprovided by treating the maleic anhydride polymers and/or copolymerswith alcohols, amines, and alkali metal hydroxides. Preferred maleicanhydride based copolymers comprise the structure represented by formula(III)

wherein x and z are any positive integer;wherein y is zero or any positive integer;R₂₁ and R₂₂ can be the same or different, and individually are hydrogen,alkyl, aryl, aralkyl, cycloalkyl, and halogen, provided that one of R₂₁and R₂₂ is an aromatic group;R₃₁, R₃₂, R₄₁ and R₄₂ are the same or different groups, which can behydrogen or alkyl of one to about five carbon atoms; andR₅₀ is functional group selected from:

a) alkyl, aralkyl, alkyl-substituted aralkyl radicals containing fromone to about twenty carbon atoms;

b) oxyalkylated derivatives of alkyl, aralkyl, alkyl-substituted aralkylradicals containing from about two to about four carbon atoms in eachoxyalkylene group, which can be of one to about twenty repeating units;

c) oxyalkylated derivatives of alkyl, aralkyl, alkyl-substituted aralkylradicals containing from about two to about four carbon atoms in eachoxyalkylene group, which can be of one to about six repeating units;

d) at least one unsaturated moiety;

e) at least one heteroatom moiety;

f) alkaline molecules capable of forming salts selected from Li, Na, Kand NH₄ ⁺; and

g) combinations thereof.

A preferred maleic anhydride polymer for LTHC layers comprises acopolymer of formula (III), wherein R₂₁, R₃₁, R₃₂, R₃₃, R₄₁, R₄₂, R₄₃,are individually hydrogen, R₂₂ is phenyl, and R₅₀ is 2-(n-butoxy)ethyl.A specific example of a maleic anhydride copolymer useful in LTHC layersis a styrene maleic anhydride copolymer such as SMA 1440H, a product ofSartomer Corporation, Exton, Pa.

In one embodiment of the invention, a preferred LTHC layer comprises oneor more water-soluble or water-dispersible radiation-absorbing cyaninecompound(s) selected from the group consisting of: indocyanines,phthalocyanines including polysubstituted phthalocyanines andmetal-containing phthalocyanines, and merocyanines; and one or morewater-soluble or water-dispersible polymeric binders selected from thegroup consisting of: acrylic resins, hydrophilic polyesters, sulphonatedpolyesters, and maleic anhydride homopolymers and copolymers.

A most preferred LTHC layer further comprises one or more releasemodifiers selected from the group consisting of: quaternary ammoniumcationic compounds; phosphate anionic compounds; phosphonate anioniccompounds; compounds comprising from one to five ester groups and fromtwo to ten hydroxyl groups; alkoxylated amine compounds; andcombinations thereof.

Metal radiation absorbers also may be used as LTHC layers, either in theform of particles or as films, as disclosed in U.S. Pat. No. 5,256,506hereby incorporated by reference. Nickel and chromium are preferredmetals for the LTHC layer 108, with chromium being especially preferred.Any other suitable metal for the heating layer can be used. Thepreferred thickness of the heating layer depends on the opticalabsorption of the metals used. For chromium, nickel/vanadium alloy ornickel, a layer of 80-100 Angstroms is preferred.

Preferred radiation absorbers for LTHC layers utilized herein areselected from the group: metal films selected from Cr and Ni; carbonblack; graphite; and near infrared dyes with an absorption maxima ofabout 600 to 1200 nm within the LTHC layer.

Additional Transfer Layer

FIG. 2A is a cross-sectional view of a thermal imaging donor 100 inaccordance with another embodiment of the invention. The thermal imagingdonor 100 comprises base film 102, an additional transfer layer 104, andmetal transfer layer 106 dispersed on the surface of layer 104.

FIG. 2B is a cross-sectional view of thermal imaging donor 100, inaccordance with another embodiment of the invention. The thermal imagingdonor 100 comprises a LTHC layer 108 interposed between base film 102and an additional transfer layer 104; and a metal transfer layer 106 onthe additional transfer layer 104.

The thermal imaging donor may have one or more additional transferlayers disposed between the base film and the metal transfer layer,defined herein as below the metal transfer layer; or on a side of themetal transfer layer opposite said base film, herein defined as abovethe metal transfer layer. The additional transfer layer thickness can beanywhere from about 5 nm to about 5 μm, and more preferably, about 100nm to about 3 μm. The additional transfer layer can be a functionallayer, acting as a conducting, semiconducting, insulating, adhesive,planarizing, light attenuating or protective layer, for instance, and istransferred along with the metal transfer layer in the thermal transferprocess. Following transfer, the additional transfer layer may lie ontop of the patterned metal layer. Alternatively, if the additionaltransfer layer is on top of the metal layer in the donor, followingtransfer, it will lie between the receiver and the metal layer.

Conducting and Resistive Layers

Conductor and resistive layers, including polymers with or withoutvarious fillers, can be useful additional transfer layers. Usefulconductive layers include Tr-conjugated organic polymers and dopedversions of these polymers. Preferred polymers fall in one or more ofthe following categories: (a) stable conducting polymers such aspolyaniline (PANI) and polyethylene dioxythiophene (PEDOT); (b) solubleor dispersable conducting polymers that form films using standardcoating techniques, including PANI, PEDOT; and other alkyl- oralkoxy-substituted derivatives of conducting polymers such as poly(2,5dialkoxy)paraphenylene vinylene and poly(3-hexyl)thiophene; and (c)conducting polymers that give high conductivity upon doping. Preferredconducting polymers, referred to herein as Conducting Polymers A, areselected from the group consisting of: polyaniline; polythiophene;polypyrrole; polyheteroaromatic vinylenes; and their derivatives.Descriptions of highly conductive polymers and methods for dopingconductive polymers can be found in the following references: Bredas,J.-L. In Handbook of Conducting Polymers; Skotheim, T., Ed.; MarcelDekker, Inc., New York, 1986, Vol. 2, Chapter 25; MacDiamid, A. G.,Angew. Chem. Int. Ed. 2001, 40, 2581-2590; and Heeger, A. J. Angew.Chem. Int. Ed. 2001, 40, 2591-2611. U.S. Pat. Nos. 5,863,465 and5,370,825 describe the conducting and semiconducting properties ofpolyanilines. Organic acids, including plasticizing acids, are preferreddopants. Additional preferred dopants are conducting nanoparticlesselected from the group consisting of: gold; silver; copper; and alloysthereof; ITO; ATO; carbon nanotubes; and mixtures thereof.

In preferred embodiments of the invention, the conductivity ofpolyanilines and derivatives thereof can be fine-tuned with dopantsincluding organic acids and, optionally, carbon nanotubes to provideappropriate levels of conductivity, as described in US 2005/0116202,hereby incorporated by reference. Preferred conductive additionaltransfer layers comprise polyaniline dispersions of single wall carbonnanotubes (SWNT), preferably about 0.1 to 12 wt % SWNTs. Preferably thepolyaniline and derivatives thereof are further doped with an organicprotonic acid having 1 to 30 carbons, the acid present at a moleequivalent amount of about 25% to about 100% of the nitrogen atoms inthe polymer backbone. A preferred organic protonic acid isdinonylnaphthalene sulfonic acid (DNNSA).

The preferred thickness of conductors useful as additional transferlayers is about 0.01 to about 10 microns, preferably about 0.1 to about5 microns, and more preferably about 0.2 to about 3 microns.

Conductive additional transfer layers can also include nonconductingpolymers doped with conductive or resistive nanoparticles. Preferrednonconducting polymers useful in formulating conductive additionaltransfer layers are Nonconducting Polymers A, defined here as selectedfrom the group consisting of: acrylic and styrenic-acrylic latexes andsolution-based acrylic and styrenic-acrylic (co)polymers includingrandom and graft copolymers and (meth)acrylate copolymers; andcombinations thereof; copolymers of ethylene with one or more monomersselected from the group consisting of: (meth)acrylate(s), vinyl acetate,carbon monoxide and (meth)acrylic acid; and polyvinylacetate and itscopolymers. Especially preferred solution-based and latex polymers ofNonconducting Polymers A have a Tg of about −50° C. to about 175° C.,and more preferably, about −30° C. to about 90° C. Especially preferredsolution-based polymers of this group are additionally characterized bya M_(w) of about 10,000 to about 200,000. Additionally preferrednonconducting polymers, referred to herein as Nonconducting Polymers B,useful in forming conductive additional transfer layers arepolyvinylpyrrolidone and its copolymers includingpolyvinylpyrrolidone-co-vinyl acetate. Preferred conductingnanoparticles as dopants are selected from the group consisting of:gold; silver; copper; and alloys thereof; ITO; ATO; carbon nanotubes;and mixtures thereof. Preferred doping is in the range of about 40 toabout 90 wt % nanoparticles.

Dielectric Layers

Dielectric layers, including insulating polymers with or without variousfillers, including pigments, can be useful additional transfer layers inthe invention. Dielectric layers especially useful in devices includeorganic polymers and polymers combined with high K dielectricnanoparticles. Herein high K dielectric nanoparticles refers tonanoparticles with a dielectric constant of 20 and above, preferably 30and above, and more preferably 100 and above.

In one embodiment of the invention, the additional transfer layer 104 isa dielectric layer having a resistivity of about 10¹⁴ ohm-cm or greatercomprising at least one layer of material, herein referred to as LayerA, comprising: one or more dielectric polymers selected from the groupconsisting of: acrylic and styrenic polymers selected from the groupconsisting of: acrylic, styrenic and styrenic-acrylic latex,solution-based acrylic, styrenic and styrenic-acrylic polymers, andcombinations thereof; heteroatom-substituted styrenic polymers selectedfrom the group consisting of: partially hydrogenatedpoly(4-hydroxy)styrene, poly(4-hydroxy)styrene, and copolymers ofpoly(4-hydroxy)styrene with hydroxyethyl (meth)acrylate, alkyl(meth)acrylate, styrene, and alkyl-substituted styrene wherein the alkylgroup is a C1 to C18 straight or branched chain alkyl group;phenol-aldehyde (co)polymers and (co)oligomers and combinations thereof;and poly(vinyl acetate); and about 0.5 wt % to about 10 wt %, based onthe dry weight of the Layer A, of one or more near-IR dye(s)characterized by an absorption maximum in the range of about 600 toabout 1200 nm within Layer A. The term dielectric polymers hereinencompasses homopolymers, copolymers derived from polymerization of twoor more monomers, post-derivatized (co)polymers including graft(co)polymers, and low molecular weight homopolymers or copolymers. Thepolymers may be linear, branched, hyperbranched or dendritic.

Preferred dielectric polymers for Layer A include acrylic, styrenic andstyrenic-acrylic latexes comprising alkyl (meth)acrylate, styrene, andalkyl-substituted styrene wherein the alkyl group is a C1 to C18straight or branched chain alkyl group. Preferred optional monomers forthese latex-based polymers include (meth)acrylic acid, hydroxyethyl(meth)acrylate and glycidyl (meth)acrylate. More preferred acrylic,styrenic and styrenic-acrylic latexes are selected from the group:Latexes A, defined herein as one or more latex resins comprising atleast about 85 wt %, preferably at least about 90 wt %, and morepreferably at least about 95 wt %, of monomers selected from the group:alkyl (meth)acrylate, styrene, and alkyl-substituted styrene wherein thealkyl group is a C1 to C18 straight or branched chain alkyl group.Preferred optional monomers for these latex resins include (meth)acrylicacid, preferably up to about 5 wt %, hydroxyethyl (meth)acrylate,preferably up to about 10 wt %, and glycidyl (meth)acrylate, preferablyup to about 5 wt %. Preferably the latexes have an average particle sizeof less than about 150 nm, more preferably, less than about 100 nm, andan acid number less than about 100, preferably less than about 75, andmore preferably less than about 25.

Particularly preferred polymers for Layer A with high resistivity (above10¹⁴ ohm-cm) are Acrylic Latexes B and Styrene-Acrylic Latexes C andcombinations thereof. Acrylic Latexes B are defined herein as one ormore acrylic latexes comprising at least about 85 wt %, preferably atleast about 90 wt %, and more preferably at least about 95 wt %, ofmonomers selected from the group consisting of: methyl methacrylate andbutyl acrylate. Styrene-Acrylic Latexes C are defined herein as one ormore styrene-acrylic latexes comprising at least about 85 wt %,preferably at least about 90 wt %, and more preferably at least about 95wt %, of monomers selected from the group consisting of: methylmethacrylate, butyl acrylate and styrene. Preferred optional monomersfor Acrylic Latexes B and Styrene-Acrylic Latexes C are selected fromthe group consisting of: (meth)acrylic acid, preferably up to about 5 wt%, hydroxyethyl methacrylate, preferably up to about 10 wt %, andglycidyl methacrylate, preferably up to about 5 wt %. Commercialexamples of acrylic and styrenic acrylic latexes useful as dielectricpolymers include Joncryl® 95 and 1915 (co)polymers (Johnson Polymer).Methods for synthesizing suitable latex polymers have been reported inWO 03/099574.

Further preferred dielectric polymers for Layer A include solution-basedacrylic, styrenic and styrenic-acrylic polymers. Herein the term“solution-based” refers to materials that are soluble in solvents suchas water and/or one or more common organic solvents including alcohols,e.g. ethanol and butoxyethanol; ethers, e.g. dimethoxyethane; esters,e.g. ethyl and butyl acetate; ketones, e.g., acetone and 2-butanone; andaromatic hydrocarbons, e.g. xylenes. Preferred solution-based acrylic,styrenic and styrenic-acrylic polymers have a M_(w) of less than about100,000, preferably less than 50,000, and more preferably less than30,000. Furthermore, preferred solution-based acrylic, styrenic andstyrenic-acrylic polymers have an acid number less than about 250.Preferred solution-based acrylic, styrenic and styrenic-acrylic polymerscomprise monomers selected from the group: alkyl (meth)acrylate, benzyl(meth)acrylate, styrene, and alkyl-substituted styrene wherein the alkylgroup is a C1 to C18 straight or branched chain alkyl group. Preferredoptional monomers for these solution-based polymers include(meth)acrylic acid and hydroxyethyl (meth)acrylate.

A particularly preferred material for Layer A is a combination of theacrylic, styrenic and styrenic-acrylic latexes and water-based acrylic,styrenic and styrenic-acrylic polymers described above. Preferably thecombination comprises about 20 wt % to about 80 wt %, more preferablyabout 40 wt % to about 80 wt %, of an acrylic or styrenic-acrylic latexfraction and about 20 wt % to about 80 wt %, more preferably about 20 wt% to about 60 wt %, of a water-based acrylic or styrenic-acrylic polymerfraction, based on the dry weight of the combination.

Other preferred dielectric polymers for Layer A includeheteroatom-substituted styrenic polymers selected from the groupconsisting of: partially hydrogenated poly(4-hydroxy)styrene,poly(4-hydroxy)styrene (PHS), and copolymers of PHS with hydroxyethyl(meth)acrylate, alkyl (meth)acrylate, styrene, and alkyl-substitutedstyrene wherein the alkyl group is a C1 to C18 straight or branchedchain alkyl group. Particularly preferred comonomers are hydroxyethylmethacrylate, butyl acrylate, methyl methacrylate and styrene withhydroxyethyl methacrylate and butyl acrylate being especially preferred.The PHS (co)polymers may be linear or branched. When PHS homopolymer isused, the branched structure is preferred Preferred (co)polymers of thisclass have a M_(w) of less than about 30,000 and preferably less thanabout 20,000 and more preferably less than about 10,000. Partiallyhydrogenated PHS refers to PHS polymers that have been hydrogenated upto about 50 equivalent % of the unsaturation within the polymer andpreferred polymers are hydrogenated to about 10 to 20 equivalent %.Commercial examples include PHS-B (branched PHS homopolymer; DuPontElectronic Technologies, Dallas, Tex.), Maruka Lyncur CMM (PHS copolymerwith methyl methacrylate; Maruzen Petrochemical Co., LTD. Tokyo, Japan),Maruka Lyncur CHM (PHS copolymer with hydroxyethyl methacrylate;Maruzen), Maruka Lyncur CBA (PHS copolymer with butyl acrylate,Maruzen), Maruka Lyncur CST 15, 50, and 70 (PHS copolymers with styrene,Maruzen), and Maruka Lyncur PHM-C (partially hydrogenated PHS, Maruzen).

Other preferred dielectric polymers for Layer A include those selectedfrom the group consisting of: phenol-aldehyde (co)polymers/(co)oligomersand combinations thereof. Preferred (co)polymers/(co)oligomers in thisclass are derived from mono- and bis-phenols and mono- and bis-aldehydesselected from the group consisting of: phenol; alkyl- andaryl-substituted phenols; formaldehyde; and alkyl-, aryl- andheteroatom-substituted aldehydes. The phenol-aldehyde resins can befurther derivatized, e.g., the hydroxy group converted to an ethergroup. Preferred (co)polymers/(co)oligomers within this group have aM_(w) of about 20,000 or less, preferably about 10,000 or less.Commercial examples include Novolac®/Novolak® resins (SchenectadyInternational Inc., Schenectady N.Y.).

Other preferred dielectric polymers for Layer A include poly(vinylacetate) homopolymer. Preferred polymers within this group have a M_(w)of about 100,000 or less.

The above polymers may be plasticized for improved flexibility,adhesion, compatibilization with an IR dye, among other characteristics.In certain instances, the plasticizer may be selected from the aboveclasses of polymers. For example, a higher Tg or higher molecular weight(MW) phenol-aldehyde polymer can be blended with a lower Tg or lower MWphenol-aldehyde polymer. Another example is PHS blended with aphenol-aldehyde polymer. Examples of suitable plasticizers for some ofthe above classes of polymers comprise poly(ethylene) glycol, glycerolethoxylate, di(ethyleneglycol) dibenzoate, and phthalate-basedplasticizers such as dibutyl phthalate. A number of potentially suitableplasticizers for various polymers and details regarding their use may befound in the following reference: “Handbook of Plasticizers,” Ed. G.Wypych, ChemTec Publishing, Toronto, Ont. 2004.

Layer A comprises about 0.5 wt % to about 10 wt %, and more preferablyabout 0.5 wt % to about 6 wt %, based on the dry weight of Layer A, ofone or more near-IR dye(s) characterized by an absorption maxima in therange of about 600 to about 1200 nm within the Layer A. Preferably thenear-IR dye is chosen such that its absorption band overlaps with theemission band of the exposure laser used in the transfer process.Typically, the exposure laser emits radiation in the near-IR range.Preferred classes of dyes are the cyanine compound(s) selected from thegroup: indocyanines, phthalocyanines including polysubstitutedphthalocyanines and metal-containing phthalocyanines, and merocyanines.A particularly preferred class of near-IR dye(s) is that of indocyaninedyes having absorption at about 830 nm. A number of suitable indocyaninedyes absorbing at around 830 nm and with solubility in differentsolvents and in water are available from H. W. Sands Co. and othersources. Preferred near-IR dyes for the invention are selected from thegroup: 3H-indolium,2-[2-[2-chloro-3-[(1,3-dihydro-1,3,3-trimethyl-2H-indol-2-ylidene)ethylidene]-1-cyclopenten-1-yl]ethenyl]-1,3,3-trimethyl-,salt with trifluoromethanesulfonic acid (1:1) having CAS No.[128433-68-1];2-(2-(2-chloro-3-(2-(1,3-dihydro-1,1-dimethyl-3-(4-sulphobutyl)-2H-benz[e]indol-2-ylidene)ethylidene)-1-cyclohexene-1-yl)ethenyl)-1,1-dimethyl-3-(4-sulphobutyl)-1H-benz[e]indolium,inner salt, free acid having CAS No. [162411-28-1]; and indolenine dyescorresponding to formulas (I) and (II) and resonance structures thereof:

Preferred dye levels in the material will give a film OD of about 0.2 orgreater, with an OD of about 0.5 to about 1.5 being preferred. To reacha preferred OD, unfilled water-based latex systems will typicallyrequire a higher dye loading of about 4 to 6 wt %. Unfilledsolution-based systems will typically require lower dye loadings ofabout 0.5 to about 2 wt %.

In another preferred embodiment the dielectric layer comprises two ormore Layers A that are gradient dye layers with each gradient dye layerindependently characterized by a dry wt % of near-IR dye of about 0.5 toabout 10 wt %; wherein at least one gradient dye layer has a lower wt %of near-IR dye, at least one gradient dye layer has a higher wt % ofnear-IR dye, and said higher wt % of near-IR dye is a value at least 20%higher than that of the lower wt % of near-IR dye.

In another preferred embodiment, the at least one Layer A furthercomprises a high K nanoparticle fraction, of about 10 to about 90 wt %based on the dry weight of Layer A, with the nanoparticle fractionhaving a dielectric constant greater than about 20, and an averageparticle size of about 5 nm to about 500 nm. Herein high K dielectricnanoparticle fraction refers to nanoparticles with a dielectric constantof about 20 and above, preferably about 30 and above, and morepreferably about 100 and above. Preferred dielectric polymers forpracticing this embodiment are selected from the group: acrylic andstyrenic-acrylic latex, solution-based acrylic and styrenic-acrylic(co)polymers, and combinations thereof; and phenol-aldehyde(co)polymers/(co)oligomers; as described above. Preferred high Kdielectric nanoparticles for practicing this embodiment are selectedfrom the group: barium titanate, strontium titanate, barium strontiumtitanate and titanium dioxide.

In another preferred embodiment the dielectric layer comprises two ormore Layers A that are gradient nanoparticle layers with each gradientnanoparticle layer independently characterized by a dry wt % of high K(high dielectric constant) nanoparticle fraction of about 10 to about 90wt %; wherein at least one gradient nanoparticle layer has a lower wt %of high K nanoparticle fraction and at least one gradient nanoparticlelayer has a higher wt % of high K nanoparticle fraction, and said higherwt % of high K nanoparticle fraction is a value at least 20% higher thanthat of the lower wt %.

In another preferred embodiment the dielectric layer further comprisesan additional dielectric layer, herein referred to as Layer B,comprising one or more dielectric polymers, characterized by aresistivity of about 10¹⁴ ohm-cm or greater. Extensive lists ofdielectric polymers can be found in WO 03/052841 and WO 06/024012.Preferred dielectric polymers for Layer B are selected from the groupconsisting of: acrylic and styrenic polymers selected from the groupconsisting of: acrylic, styrenic and styrenic-acrylic latexes,solution-based acrylic, styrenic and styrenic-acrylic polymers, andcombinations thereof; heteroatom-substituted styrenic polymers selectedfrom the group consisting of: partially hydrogenatedpoly(4-hydroxy)styrene, poly(4-hydroxy)styrene, and copolymers ofpoly(4-hydroxy)styrene with hydroxyethyl (meth)acrylate, alkyl(meth)acrylate, styrene, and alkyl-substituted styrene wherein the alkylgroup is a C1 to C18 straight or branched chain alkyl group;phenol-aldehyde (co)polymers and (co)oligomers and combinations thereof;and poly(vinyl acetate), as described above. This embodiment can befurther practiced including other embodiments disclosed above. Preferredoptional additives for Layer B include carbon black and high Knanoparticles with preferred high K dielectric nanoparticles forpracticing this embodiment selected from the group consisting of: bariumtitanate, strontium titanate, barium strontium titanate and titaniumdioxide.

In another preferred embodiment the additional transfer layer has aresistivity of 10¹⁴ ohm-cm or greater and comprises at least one layerof material, herein referred to as Layer C, comprising one or moredielectric polymer(s) selected from the group consisting of: acrylic,styrenic and styrenic-acrylic latexes; comprising at least about 85 wt %of monomers selected from the group consisting of: alkyl (meth)acrylate,styrene, and alkyl-substituted styrene wherein the alkyl group is a C1to C18 straight or branched chain alkyl group. This embodiment can befurther practiced including other embodiments disclosed above. In oneembodiment Layer C further comprises a high K nanoparticle fraction, upto about 90 wt % of the dry weight of Layer C, with the nanoparticlefraction having a dielectric constant greater than about 20, and anaverage particle size of about 5 nm to about 500 nm. Preferred optionaladditives for Layer C include carbon black and high K dielectricnanoparticles with preferred high K dielectric nanoparticles forpracticing this embodiment selected from the group: barium titanate,strontium titanate, barium strontium titanate and titanium dioxide.

The Tg's of the dielectric polymers utilized in Layer A, Layer B andLayer C range from about −30 to about 150° C., preferably about 20 toabout 90° C. and most preferably about 30 to about 70° C. Typically, theaddition of fillers enables the utilization of lower Tg polymers and theaddition of plasticizers enables the utilization of higher Tg polymers.The preferred Tg of the dielectric layer itself and of the layersutilized in the dielectric layer, including Layer A, Layer B, and LayerC is about 30 to about 100° C., preferably about 40 to about 85° C. andmost preferably about 45 to about 65° C.

Layer A, optional Layer B and Layer C may include additives such asfillers, surfactants, defoamers, dispersants and grinding aids. Numeroussurfactants, defoamers, dispersants and grinding aids are available thatare suitable for this purpose. Selection will often be based uponobserved coating and dispersion quality and the desired adhesion of thedielectric layer to other layers in the thermal transfer process. Incertain embodiments, the surfactants comprise siloxy-, fluoryl-, alkyl-and alkynyl-substituted surfactants. These include the Byk® (BykChemie), Zonyl® (DuPont), Triton® (Dow), Surfynol® (Air Products) andDynol® (Air Products) surfactants. Preferred are Byk® 345, 346 and 348and Zonyl® FSO and FSN surfactants. In certain embodiments, thedefoamers comprise alkyl and alkynyl functionality and include Surfynol®defoamers. In certain embodiments, the dispersants comprisefunctionalized polymers, oligomers and monomers and include Surfynol®and Disperbyk® dispersants.

The preferred thickness of the dielectric layer and of the layersutilized in the dielectric layer, including Layer A, Layer B and LayerC, is about 0.05 to about 10 microns, preferably about 0.1 to about 5microns, and more preferably about 0.2 to about 3 microns.

Dielectric polymers filled with light-absorbing pigments make usefuladditional transfer layers. Such layers are particularly useful whenused below or on top of a metal transfer layer such as silver. Apreferred pigment for this purpose is carbon black. Preferredcompositions are about 1 wt % to about 90 wt % carbon black.

Preparation of the Thermal Imaging Donor

The thermal imaging donor comprising a metal transfer layer is preparedby applying the fluid dispersion of the metal composition onto thesurface of the thermal imaging substrate and volatizing the carrierfluid. Applying the fluid dispersion can be accomplished by any methodthat gives a uniform layer, or if desired, a patterned or nonuniformmetal transfer layer. Coating, including rod coating and spin-coating,spraying, printing, blading or knifing can be used. Coating and sprayingare preferred methods for applying the fluid dispersion to provideuniform metal transfer layers. The carrier fluid is allowed to evaporateto provide the metal transfer layer or the layer can be dried by anyconventional method of drying including applying heat and/or vacuum.

The thermal imaging donor optionally can comprise one or more additionaltransfer layers deposed on top of, or below, the metal transfer layer.FIG. 3A is a cross-sectional view of a thermal imaging donor 100 inaccordance with another embodiment of the invention. The thermal imagingdonor 100 comprises base film 102, metal transfer layer 106 and anadditional transfer layer 110 on top of the metal transfer layer. FIG.3B is a cross-sectional view of a related thermal imaging donor 100further including a LTHC layer 108 interposed between base film 102 andthe metal transfer layer 106. FIG. 3C is a cross-sectional view of arelated thermal imaging donor 100, wherein an additional transfer layer104, is interposed between the LTHC layer 108 and metal transfer layer106, and an additional transfer layer 110 is on top of the metaltransfer layer.

A particularly preferred embodiment of the invention includes anadditional transfer layer that is a light attenuating layer. Lightattenuating layers can be used to minimize the visibility of the metaltransfer layer in the final electronic device, and can be deposed oneither side or both sides of the metal transfer layer as an additionaltransfer layer. Preferably the light attenuating layer is comprised ofthe preferred dielectric materials discussed above and a visible lightabsorbing dye or pigment. A preferred pigment is carbon black.

Optionally, a protective strippable cover sheet may be present on theoutmost layer of the thermal transfer donor. The cover sheet protectsthe underlaying transfer layers and is easily removable.

Thermal Imaging Receiver

FIG. 4 is a cross-sectional view of thermal imaging receiver 200, inaccordance with one embodiment of the invention, including a receiverbase film 202 and optional adhesive layer 204. The receiver base film202 is a dimensionally stable sheet material as defined for the basefilm of the thermal imaging donor. Additionally, the receiver base filmcan be an opaque material, such as polyethylene terephthalate filledwith a white pigment such as titanium dioxide; ivory paper; or syntheticpaper, such as Tyvek® spunbonded polyolefin. The sheet material can alsobe glass. Preferred base films for receivers are polyethyleneterephthalate, polyethylene naphthalate, polyimide (Kapton®) and glass.

The optional adhesive layer 204 facilitates adhesion of the thermalimaging receiver 200 to the thermally imaged transfer layer. Suitableadhesive layers 204 comprise any of the(co)polymers/co(oligomers)/resins mentioned above in the description ofthe additional transfer layer. Preferred image receiving layers hereinare Acrylic Latexes A, as defined above.

Patterned Multilayer Compositions

The various embodiments of thermal imaging donors and receivers definedabove are useful in providing a patterned multilayer composition, alsoof the invention, comprising: (a) one or more base film(s); and (b) oneor more patterned metal layer(s); wherein the patterned metal layer(s)has a pattern comprising at least one line of width of about 1millimeter or less, and comprises the metal composition (A), asdisclosed above. Preferably the patterned metal layer has at least atleast one line of width of about 200 microns or less. In otherembodiments the patterned metal layer has at least one line of width ofabout 150 microns or less, 100 microns or less, 50 microns or less, 20microns or less and 10 microns or less. Preferably the multilayercomposition has a resistivity of about 10⁻² ohm-cm or less andpreferably about 10⁻⁴ ohm-cm or less.

The patterned multilayer compositions can further include additionalpatterned layers disposed between said base film and the patterned metallayer, herein defined as below the patterned metal layer; or on a sideof the patterned metal film opposite said base film, herein defined asabove the patterned metal layer. The additional patterned layers, andtheir preferred embodiments, correspond to those materials and layersdisclosed above as useful and preferable for additional transfer layers.

The patterned multilayer composition is useful as electronic circuitsfor electronic devices such as thin film transistors, displays, andtouch pads. In a preferred application the patterned multilayercomposition is useful as an electromagnetic interference (EMI) shieldthat may be used to shield electronic devices from outside radiation,and shield the local environment from radiation emitting from thedevice. A typical example of a device is a plasma display panel (PDP)which generates a large amount of electromagnetic radiation. Usually, afront panel is disposed in front of the PDP to shield electromagneticradiation. The front panel must have a shielding function of 30 decibel(dB) or above in the range of 30 MHz to about 1 GHz to shieldelectromagnetic radiation emitted from the screen of the display. Thisis usually accomplished with a very thin pattern of metal mesh mountedon a transparent base film. The metal mesh (lines) of the EMI shieldshould not deteriorate visibility and should have a proper transparency.Typically the metal mesh is provided by a photolithographic process, asdescribed, for instance, in US patent application 2006/0088690 A1

Base films useful in EMI shields include transparent inorganic compoundssuch as glass or transparent polymers such as acrylic or polycarbonate.Specific examples include PET, polysulfone, polyethersulfone,polystyrene, polyethylene naphthalate, polyacrylate, polyetherketone,polycarbonate, polypropylene, polymethyl methacrylate. Preferred basefilms for EMI shields of the invention are selected from the groupconsisting of: polyethylene terephthalate, polyethylene naphthalate,triacetyl cellulose and glass.

Another embodiment of the invention is the electromagnetic shielddescribed above, further comprising an additional patterned layerdisposed below the patterned metal layer, or above the patterned metallayer. Preferably this additional patterned layer is a light-attenuatinglayer; and most preferably the additional patterned layer comprisesabout 1 to about 90 wt % carbon black.

Preferably the EMI shield further comprises an antireflection layer on asurface, on the viewing side, of the base film. An antireflection filmis generally disposed on an outermost surface of an image display devicesuch as an optical lens, cathode ray tube display device (CRT), plasmadisplay panel (PDP), liquid crystal display device (LCD), or organicelectroluminescent device, to reduce reflectance so as to preventoptical interference from external light. There are various commerciallyavailable single-layer and multiple-layer antireflection films. Amultiple-layer antireflection film consists of alternatehigh-diffraction and low-diffraction layers. Suitable high-diffractionlayers are those of niobium oxide, titanium oxide, zirconium oxide andITO. Suitable low-diffraction layers are those of silicon oxide,magnesium fluoride and such. Some antireflection film has a layer havinga minutely roughened surface that reflects external light in a diffusedreflection mode. For a general reference on antireflective materials andcoatings, see: Dobrowolski, J. A. In Handbook of Optics; Bass, M. Ed.;McGraw-Hill, Inc.: New York, 1995; Vol. 1, Chapter 42.

Another embodiment of the invention is a touchpad sensor comprising amultilayer composition having a patterned metal layer as describedabove. Preferably the touchpad sensor comprises a dielectric layer asdisclosed in the section entitled “Dielectric layers” above. In oneembodiment the touchpad sensor comprises a first base film with a firstpatterned metal layer; a second base film with a second patterned metallayer; and a dielectric layer deposed between the first and secondpatterned metal layers. In another embodiment the touchpad sensorcomprises a first base film, having two opposing surfaces, a patternedmetal layer deposed on each of the two opposing surfaces; and adielectric layer on top of each of the patterned metal layers.

Thermal Transfer to Provide Patterned Multilayer Compositions

To provide patterned multilayer compositions the thermal imaging donoris contacted with a thermal imaging receiver. By contacted is meant thatthe donor is in close proximity, preferably within several microns, ofthe receiver. The receiver may be off-set from the donor by, forexample, previously printed layers, fibers or particles that act asspacers to provide a controlled gap between donor and receiver. Vacuumand/or pressure can be used to hold the donor element 100 and thereceiver element 200 together. As one alternative, the donor element 100and the receiver element 200 can be held together by fusion of layers atthe periphery of the assembly.

At least a portion of the metal transfer layer, and optionally a portionof one or more additional transfer layers, is transferred to the thermalimaging receiver by thermal transfer to form a patterned metal layer.Thermal transfer can be achieved by a laser-mediated transfer process.In one embodiment, the assembly of the donor element 100 and thereceiver element 200 is selectively exposed to heat, which is preferablyin the form of laser radiation, in an exposure pattern of the image ofthe desired pattern to be formed on the substrate. The laser radiationis focused about at the interface between those layers to be transferredand those to remain with the donor. For instance, if an LTHC layer ispresent the laser is focused on the interface between the LTHC layer andthe metal layer. Sufficient radiation is applied to achieve transfer ofthe desired transfer layers to the receiver.

A variety of light-emitting sources can be used to heat the thermaltransfer donor elements. For analog techniques (e.g., exposure through amask), high-powered light sources (e.g., xenon flash lamps and lasers)are useful. For digital imaging techniques, infrared, visible, andultraviolet lasers are particularly useful. Other light sources andirradiation conditions can be suitable based on, among other things, thedonor element construction, the transfer layer material, the mode ofthermal transfer, and other such factors.

The radiation is preferably applied through the backside of base film102, that is, the side not containing the metal transfer layer. Laserradiation preferably is provided at a laser fluence of up to about 600mJ/cm², and more preferably about 75-440 mJ/cm². Various types of laserscan be used. The laser preferably emits in the infrared, near-infraredor visible region. Particularly advantageous are diode lasers emittingin the region of 750 to 870 nm which offer a substantial advantage interms of their small size, low cost, stability, reliability, ruggednessand ease of modulation. Diode lasers emitting in the range of 780 to 850nm are most preferred. Such lasers are available from, for example,Spectra Diode Laboratories (San Jose, Calif.). Other types of lasers andlasers, which emit in other wavelength bands, may be used as well. Onedevice used for applying an image to the receiver is the Creo SpectrumTrendsetter 3244F, which utilizes lasers emitting near 830 nm. Thisdevice utilizes a Spatial Light Modulator to split and modulate the 5-50Watt output from the ˜830 nm laser diode array. Associated optics focusthis light onto the imageable elements. This produces 0.1 to 30 Watts ofimaging light on the donor element, focused to an array of 50 to 240individual beams, each with 10-200 mW of light in approximately 10×10 to2×10 micron spots. Similar exposure can be obtained with individuallasers per spot, such as disclosed in U.S. Pat. No. 4,743,091. In thiscase each laser emits 50-300 mW of electrically modulated light at780-870 nm. Other options include fiber-coupled lasers emitting 500-3000mW and each individually modulated and focused on the media. Such alaser can be obtained from Opto Power in Tucson, Ariz.

After exposure, the donor element 100 and the receiver element 200 areseparated, as illustrated in FIGS. 5A and 5B, leaving the untransferredportions of the metal transfer layer 106 on the donor element 100 andthe patterned metal transfer layer 106 on the receiver element 200.FIGS. 6A and 6B illustrate the embodiment wherein an additional transferlayer 104 is transferred along with the metal transfer layer to thereceiver 200. FIG. 7 is a cross-sectional view of an alternative thermalimaging receiver 200 comprising a base film 202 and at least onepatterned layer 205. Patterned layer 205 can be selected from a groupconsisting of patterned semiconductor layers, patterned conductor layersand patterned dielectric layers.

The patterned multilayer composition can be provided by the spent donorelement (a negative of the image), the imaged receiver element (apositive of the image), or both elements. Furthermore, either or both ofthe spent donor element and the imaged receiver element may be utilizedas the permanent substrate or the image may be transferred from thespent donor or receiver, preferably by lamination, to the permanentsubstrate.

Usually the transferred portions of the transfer layers correspond tothose portions of the transfer layers exposed to laser radiation. Insome instances, depending upon the nature of the donor and receiverelements and the transfer processing parameters, when the donor element100 and the receiver element 200 are separated, the receiver elementincludes both exposed portions and non-exposed portions of one or moretransfer layers. A process for enhancing the resolution of a pattern ona thermal imaging receiver comprising an exposed portion and anon-exposed portion of one or more thermal transfer layers on a surfaceof the thermal imaging receiver comprises: (a) contacting said surfaceof the thermal imaging receiver with an adhesive surface to provide atemporary laminate; and (b) removing said adhesive surface from thetemporary laminate to provide a thermal imaging receiver with a surfacesubstantially free of said non-exposed portion of one or more transferlayers. Suitable adhesive surfaces for performing the process arecommercial adhesive tapes, for instance, those Scotch® brand tapesavailable from 3M company. Tacky rollers, for instance, a medium tackroller available in the form of a Dust Removal System-1 (red) from SDI(Systems Division, Inc., Irvine, Calif. 92618-2005) are a suitableadhesive surface for the process. Chrome films, used as LTHC layersdescribed above, also make useful low tack adhesive layers for removingnon-exposed portions of the transfer layers under very gentleconditions.

Various electrical elements that can be formed, at least in part, by theuse of the present invention include electronic circuitry, resistors,capacitors, diodes, rectifiers, electroluminescent lamps, memoryelements, field effect transistors, bipolar transistors, unijunctiontransistors, thin film transistors, metal-insulator-semiconductorstacks, organic transistors, charge coupled devices,insulator-metal-insulator stacks, organic conductor-metal-organicconductor stacks, integrated circuits, photodetectors, lasers, lenses,waveguides, gratings, holographic elements, filters (e.g., add-dropfilters, gain-flattening filters, cut-off filters, and the like),splitters, couplers, combiners, modulators, sensors (e.g., evanescentsensors, phase modulation sensors, interferometric sensors, and thelike), optical cavities, piezo-electric devices, ferroelectric devices,thin film batteries, or combinations thereof; for example, thecombination of field effect transistors and organic electroluminescentlamps as an active matrix array for an optical display.

Materials

Unless otherwise indicated, chemicals were used as received withoutfurther purification. Polymers, plasticizers, IR dyes, and surfactantswere obtained from the sources listed in the specification or purchasedfrom Aldrich. Pigments such as carbon black dispersions were obtainedfrom Penn Color, Inc., Doylestown, Pa. Silver nanoparticles werepurchased from Ferro Co.—Electronic Material Systems; Nanostructured &Amorphous Materials, Inc., and Mitsui Co. HiPco Raw CNt's were purchasedform Carbon Nanotechnologies, Inc., Houston Tex.

Donor Substrates

Cr LTHC Layer. A base film of polyethylene terepthalate (PET, 50 micronsthick in all examples unless stated otherwise) was coated with chromemetal in a vacuum deposition chamber by CP Films of Martinsville, Va.Metallization was carried out on PET films with and without lightattenuating agents (670 nm absorbers). The chrome layer was coated atboth 50% T and 40% T. In the examples, these donor films will bereferred to as: 40% T Cr PET donor substrate and as 50% T Cr PET donorsubstrate; for the metallized films without light attenuating agents.The donor films with 670 nm absorbers incorporated in the base film willbe referred to as: 40% T Cr Blue PET donor substrate and as 50% T CrBlue PET donor substrate.

Organic LTHC Layer. The organic LTHC layer was prepared as reported inFormulation L of the Examples of PCT/US05/38009, referenced above:

A LTHC coating formulation was prepared from the following materials:(i) demineralised water: 894 g; (ii) dimethylaminoethanol: 5 g; (iii)Hampford dye 822 (Hampford Research; formula corresponds to SDA 4927):10 g;_(iv) polyester binder (Amertech Polyester Clear; American Inks andCoatings Corp; Valley Forge; Pa.): 65 g of a 30% aqueous solution; (v)TegoWet™ 251(4) (a polyether modified polysiloxane copolymer,Goldschmidt): 2.5 g; (vi) potassium dimethylaminoethanol ethylphosphate: 14 g of an 11.5% aqueous solution [The 11.5% aqueous solutionwas prepared by combining three parts water and 0.5 parts ethyl acidphosphate (Stauffer Chemical Company, Westport, Conn.: Lubrizol,Wickliffe, Ohio) and sufficient 45% aqueous potassium hydroxide toachieve a pH of 4.5, followed by addition of sufficientdimethylaminoethanol to achieve a pH of 7.5 and finally dilution withwater to achieve five parts total of final aqueous solution of 11.5relative mass percent of water-free compound.]; (vii) crosslinker Cymel™350 (a highly methylated, monomeric melamine formaldehyde resin, CytecIndustries Inc. West Paterson, N.J.): 10 g of a 20% solution; and (viii)ammonium p-toluene sulphonic acid: 2 g of a 10% aqueous solution.

Ingredients (ii) and (iii) were added to the water and allowed to stirfor up to 24 hours before addition of the other ingredients in the ordershown. There was no need to filter this formulation. The formulation wasapplied in an in-line coating technique as follows: A PET base filmcomposition was melt-extruded, cast onto a cooled rotating drum andstretched in the direction of extrusion to approximately 3 times itsoriginal dimensions at a temperature of 75° C. The cooled stretched filmwas then coated on one side with the LTHC coating composition to give awet coating thickness of approximately 20 to 30 μm. A direct gravurecoating system was used to apply the coatings to the film web. A 60QCHgravure roll (supplied by Pamarco) rotates through the solution, takingsolution onto the gravure roll surface. The gravure roll rotates in theopposite direction to the film web and applies the coating to the web atone point of contact. The coated film was passed into a stenter oven ata temperature of 100-110° C. where the film was dried and stretched inthe sideways direction to approximately 3 times its original dimensions.The biaxially stretched coated film was heat-set at a temperature ofabout 190° C. by conventional means. The coated polyester film is thenwound onto a roll. The total thickness of the final film was 50 μm; thedry thickness of the transfer-assist coating layer is of 0.07 μm. ThePET base film contained either Disperse Blue 60 or Solvent Green 28 dyeto give a final dye concentration of typically 0.2% to 0.5% by weight inthe polymer of the base film. The base film containing the Disperse Blue60 dye (0.26% by weight) had an absorbance of 0.6±0.1 at 670 nm, and anabsorbance of <0.08 at 830 nm. The base film containing the SolventGreen 28 dye (0.40% by weight) had an absorbance of 1.2 at 670 nm, andan absorbance of <0.08 at 830 nm. These donor substrates will herein bereferred to as: Organic LTHC Blue PET donor substrate and Organic LTHCGreen PET donor substrate.

Conductor Electrical Characterization

The sheet resistance and resistivity of conducting lines were obtainedby measuring the resistance of lines with known geometries. A CascadeMicroTech (Beaverton, Oreg.) probestation model Alessi REL-6100 and asemiconductor parameter analyzer Agilent Technologies (Palo Alto,Calif.) model 4155C were used to apply a current across the lines andmeasure voltage drops at two known positions within the line. Typically,currents were swept from 1×10⁻⁵ to −1×10⁻⁵ A to obtain voltages in themV to V range. The slope of the I-V curve and the line geometry wereused to obtain resistance, sheet resistance and resistivity. From thesevalues conductivity and conductance can be calculated.

The present invention is further defined in the following Examples. Itshould be understood that these Examples, while indicating preferredembodiments of the invention, are given by way of illustration only.From the above discussion and these Examples, one skilled in the art canascertain the essential characteristics of this invention, and withoutdeparting from the spirit and scope thereof, can make various changesand modifications of the invention to adapt it to various uses andconditions.

Example 1

This illustrates formulation of a 90 wt % silver nanoparticle-dispersantcomposition used in this invention. A mixture of Ag powder (22.530 g,particle size d50=220 nm and d90=430 nm), 20% Elvacite® 2028 (12.550 g,20 wt % in xylenes made from Elvacite® 2028, Lucite International,Inc.), xylenes (12.516 g) and di(ethylene glycol) dibenzoate (0.048 g)was treated with a sonication probe (Dukane Co. Model 40TP200,Transducer Model 41C28) for 15 min, during which time the mixture wasstirred with a spatula at 5 min intervals. The container with themixture was placed in a water bath with sonication for 1 h, during whichtime the mixture was stirred with a spatula at 0.5-h intervals. Themixture was then treated in a water bath at RT with probe sonication foradditional 15 min, during which time the mixture was stirred gently witha spatula at 5-minute intervals. The resulting dispersion was filteredtwice with 2.0 Whatman® MGF-150 syringe-disc filter (Whatman Inc.,Clifton, N.J.).

Examples 2-15

Further examples 2-4, 6, 10-11, and 13-15, listed in Table 1 wereprepared in a similar fashion with the following exceptions: in Example3 the dispersion was filtered with 1.0 Whatman® MGF-150 syringe-discfilter; in Example 4 the dispersion was filtered through 12 and 8stainless steel screens (Twill Dutch Weave, mesh count 200×1400 and325×2300, absolute filter rating: 12-14 and 8 microns, Sefar AmericaInc., Depew, N.Y.); in Example 6 water was the solvent; in Example 10methanol was the solvent; and in Example 11 isopropanol was the solvent.

Further Examples 5, 7-9 and 12 were prepared in a similar fashion toExample 1 except that there was no first 15 min probe sonication and thedispersions were treated in a water bath at RT with sonication for 2hour (vs 1 hour), followed with a sonication probe for 10 min, duringwhich time the mixtures were stirred gently with a spatula at 2-3 minintervals. The resulting dispersions were filtered with 2.0μ Whatman®MGF-150 syringe-disc filters with these exceptions: in Example 9 nofiltration was used; in Example 12 filtration used 12μ screen; inExample 7 water was the solvent; and in Example 12, CNT waspre-dispersed with sonication probe for 15 min.

TABLE 1 Metal compositions of the invention. Metal Powder DispersantAdditives d50/d90 Dry wt Dry Ex. No. M/Loading % (nm) Wt. (g) ID Wt %(g) ID wt. (g) 1 Ag/90 220/430 22.550 Elvacite ® 20 2.510 A 0.048 2028 2Ag/89 350/730 20.028 Elvacite ® 20 2.478 A 0.050 2028 3 Ag/87.5 340/55011.795 Elvacite ® 20 1.691 — — 2028 4 Ag/94     870/1780 F 18.802Elvacite ® 20 1.201 A 0.020 2028 5 Ag/87.5 220/430 10.504 Elvacite ® 201.501 — — 4069 6 Ag/87.5 220/430 21.874 Joncryl ® 45/20 2.501/ B 0.436538/647 0.641 7 Ag/85 220/430 5.432 Joncryl ® 30 0.965 B 0.131 63 8Ag/93 220/430 8.932 Elvaloy ® 10 0.672 — — HP771 9 Ag/90 220/430 4.390Elvax ® 5 0.488 — — 200W 10 Ag/89 220/430 17.800 PVP 20 2.510 — — 11Ag/89 220/430 17.790 PVP- 20 2.510 — — PVA 12 Ag/87.5 350/730 10.507Elvacite ® 20 1.501 C, D 0.009, 2028 0.013 13 Ag/90 220/430 22.503Elvacite ® 20 2.501 A, C 0.060, 2028 0.072 14 Ag/89 350/730 10.018Elvacite ® 20 1.242 A 0.029 2028 15 Ag/89 350/730 20.026 Elvacite ® 202.477 A, E 0.057, 2028 0.043 PVP = polyvinylpyrrolidone; PVP-PVA =poly(vinylpyrrolidone-vinylacetate); F = equivalent spherical diameterof flake. Additives: A = di(ethylenegylcol)dibenzoate; B = Zonyl ® FSA;C = Disperbyk ® 163; D = carbon nanotubes; E = SDA 4733 IR dye.

Donor Preparation

Coating of transfer and other layers onto donor and receiver elementswas carried out utilizing stainless steel wrapped and formed 0.5 inchdiameter coating rods (R.D. Specialties, Inc., Webster, N.Y.) andchrome-plated stainless steel formed 0.625 inch diameter rods with a CNprofile (Buschman Corporation, Cleveland, Ohio). The donor free surfacewas cleaned with a pressurized nitrogen stream immediately prior tocoating to rid the surface of particle contamination. The coatings weredrawn by hand on a smooth glass surface or machine-coated utilizing aWaterProof® Color Versatility coating system (E.I. DuPont De Nemours,Inc., Wilmington, Del.).

Donors were stored in a controlled temperature/humidity environment withan average temperature of about 68° F. and about 40-50% average relativehumidity.

The dispersions from Example 1, 5, and 7-12 were coated onto 40% T CrPET substrates and dried at about 40° C. for 20 min.

The dispersions from Examples 2, 3 and 13 were coated onto organic LTHCBlue PET donor substrates and dried at about 43° C. for 20 min. Thedispersions from Examples 4, 6 and 15 were coated on organic LTHC GreenPET donor substrate and dried at about 45° C. for 20 min. The dispersionfrom Example 14 was coated on Melinex® 453 and dried at 46° C. for 20min.

General Procedure for the Preparation of Aqueous Transfer Layers

A water solution was prepared by combining the specified amounts ofwater and, optionally, a 3 wt % ammonium hydroxide solution. Next, theIR dye, one-fourth of the water solution, and optional defoamers,surfactants and plasticizers were combined in a brown glass containerand mixed well. The optional second binder was weighed in a containertogether with one-fourth of the water solution and mixed well. Optionalpigment(s) were weighed in another container with one-fourth of thewater solution and mixed well. Optional crosslinker(s) were weighed inanother container with one-fourth of the water solution and mixed well.The binder was weighed in a large container with a stir bar and anyremaining water solution was added. The contents of the second binderdispersion, the IR dye dispersion, the pigment dispersion and thecrosslinker dispersion were slowly added to the stirring binder. Afterstirring for at least 15 additional minutes, the formulation wasfiltered into a brown or foiled-coated container. Syringe filters with0.45 micron pore size were used unless specified otherwise (25 mm GD/XGlass Microfiber GMF with Propylene Housing; Cat. No. 6894-2504 Whatman,Whatman Inc., Clifton, N.J.).

Example 16

This example illustrates the preparation of a donor of the inventionwherein the metal composition of Example 1 was applied to a thermalimaging substrate comprising a base film, an organic LTHC layer and ablack acrylic latex carrier layer

A black transfer layer formulation was prepared, following the generalprocedure described above, using 11.18 g of Joncryl 538 (45 wt %), 0.025g of SDA 2860, 0.050 g of Byk® 348, 1.820 g of Carbon Black AcroversePaste 32B56 (33 wt %; Penn Color), and 18.72 g of water to give aformulation with a pH of 9.10. The resulting solution was coated ontothe Organic LTHC-Green PET donor substrate with a CN#2 formed Buschmanrod at 9.8 ft/min and dried at 45° C. for 6 minutes. The wt % solids ofthe final dry coating was: 88.2 wt % Joncryl 538, 0.4 wt % SDA 2860, 0.9wt % Byk 348, and 10.5 wt % Black 32B56.

The dispersion from example 1 was coated onto the black carrier layer ata speed of 5.8 ft/min with #6 CN formed Buschman rod and dried at 42° C.for 20 minutes.

Sheet resistance was measured according to the standard procedure givenabove. RSH<1 ohm/sq was measured for lines printed at drumspeed 40 at7.25 W and above.

Example 17

This example illustrates the preparation of a donor of the inventionwherein the metal composition of Example 1 was applied to a thermalimaging substrate comprising a base film, a chrome LTHC layer and ablack soluble acrylic carrier layer, and transferred to a thermalimaging receiver.

A black carrier layer formulation was prepared using 14.14 g of Joncryl®63 (30 wt %), 0.025 g of SDA 2860, 0.50 g of Byk® 348 (10 wt %), 2.70 gof Carbon Black Acroverse Paste 32B56 (33 wt %; Penn Color), 2.50 g ofglycerol ethoxylate (20 wt %), and 11.94 g of water to give aformulation with a pH of 8.96. The resulting solution was coated onto a40% T Cr Blue PET donor substrate (˜35 by 20.5 cm) with a CN#2 formedBuschman rod at 9.8 ft/min and dried at 45° C. for 6 min. The wt %solids of the final dry coating was: 74.32 wt % Joncryl 63, 0.4 wt % SDA2860, 0.9 wt % Byk® 348, 15.6 wt % Black 32B56 and 8.8 wt % glycerolethoxylate.

The dispersion from Example 1 was coated onto the black carrier layer ata speed of 5.8 ft/min with a #6 CN formed Buschman rod and dried at 42°C. for 20 min.

Example 18-21 Thermal Imaging Equipment and Donor Mounting

Creo Trendsetter® 800 (Creo/Kodak, Vancouver, Canada) was utilized. TheCreo Trendsetter® 800 was a modified drum-type imager utilizing amodified Thermal 1.7 Head with a 12.5 watt maximum average operatingpower at a wavelength of 830 nm with 5080 dpi resolution. The 800Trendsetter was operated in a controlled temperature/humidityenvironment with an average temperature of ˜68° C. and an averagerelative humidity of ˜40-50%. For each printing experiment, a section ofthermal imaging receiver was positioned on the drum. The thermal imagingdonor was loaded so that the side of the donor element coated with thetransfer layer was facing the free side of the receiver. Imagingassemblages were exposed from the back side through the donor film base.Films were mounted using vacuum hold down to a standard plastic or metalcarrier plate clamped mechanically to the drum. In some experimentsutilizing the Creo Trendsetter® 800 thermal platesetter, a nonstandarddrum with vacuum holes machined directly onto the drum to match commondonor and receiver sizes was used as a replacement for the standarddrum/carrier plate assemblage. Contact between the donor and receiverwas established by ˜600 mm of Hg vacuum pressure. Laser output was undercomputer control to build up the desired image pattern. Laser power anddrum speed were controllable and were adjusted in an iterative fashionto optimize image quality as judged by visual inspection of thetransferred image on the receiving surface.

The Examples illustrates printing of the donor onto receiver of theinvention. A section of thermal imaging receiver (Melinex® ST 504 film,DuPont Teijin Film) was loaded into a Creo Trendsetter® 800 thermalplatesetter. Subsequently, a thermal-imaging donor fashioned asdescribed above using the composition of example 1 was loaded so thatthe Ag coated side of the donor was facing the receiver. Contact betweenthe donor and receiver was established by 600 mm of Hg vacuum pressure.Using the Creo Trendsetter® 800 thermal platesetter a conductor patternwas imaged. The donor element was imaged at 8.7, 8.8, 8.9, 10.5, 11.0and 11.5 W, surface depth at 60 and drumspeed at 170 and 175 rpm.Immediately after imaging, the Donor/Receiver sheets were removed andpeeled apart to provide a printed layer on the receiver.

Other donors prepared using compositions from examples 2, 16 and 17 wereprinted using conditions listed in Table 2. Patterned metal layersprovided by examples 18 and 19 are shown in FIGS. 8 and 9.

TABLE 2 Printing examples of the invention Printing Condition LowestDrum Surface Resistivity Ex. Speed Depth Laser Pattern (Ohms- No. Donor(rpm) (micon) Power (W) Printed cm) 18 Ex 1 170, 175 60 8.7, 8.8, A 5.3× 10⁻⁵ 8.9, 10.5, FIG. 8 11.0, 11.5 19 Ex 2 100 50, 60, 9, 11 A 1.8 ×10⁻⁵ 101 FIG. 9 20 Ex 16 40, 80, 71 5.75-8.00 B   8 × 10⁻⁵ 120 at 0.25increments 21 Ex 17 40, 70, 71 3.50-6.50 B   7 × 10⁻⁵ 100 at 0.25increments 22 Ex 22 160 45 2.5, 4, 6, 8, No print 10, 12 23 Ex 23 160 452.5, 4, 6, 8, No print 10, 12 A: 10 micron lines with spacing B: 50, 100and 200 micron lines with spacing.

Example 22 Comparative

Poly(propylene carbonate) (3.102 g, Aldrich, Mn=50,000) was added intoDimethylacetamide (DMAC) (13.86 g ) and stirred overnight. Into thissolution was added silver trifluoroacetate (7.101 g) and the mixture wasstirred until dissolved (2 h). Ag powder (25.899 g, particle sized50=220 nm and d90=430 nm) and DMAC (10.0 g) were added to the mixtureand the slurry dispersed and filtered as in Example 1 The dispersion (8mL) was coated onto a 40% T Cr-PET donor substrate using a ColorVersatility coater at 5.8 ft/min with #6 CN formed and dried at 42° C.for 45 min. The film did not transfer at all when using the sameprocedure as Example 18 under a wide range of exposures.

Example 23 Comparative

Poly(propylene carbonate) (3.102 g, Aldrich, Mn=50,000) was added intoDMAC (23.855 g ) and stirred overnight. Into this solution was added Agpowder (33.044 g, particle size d50=220 nm and d90=430 nm). The slurrywas dispersed and filtered as in example 1. The dispersion (8 mL) wascoated onto a 40% T Cr-PET donor substrate using a Color Versatilitycoater at 5.8 ft/min with a #7 CN formed rod and dried at 43° C. for 45min. The film did not transfer at all using the procedure of Example 18under a wide range of exposures.

The comparative examples, similar to formulations described in WO03/035279, exhibited no transfer to receiver sheets, demonstrating thatknown compositions comprising conventional binders and silver powderswere not sufficient to provide the desired patterned metal layers.

Example 24

This example illustrates the preparation of an EMI shield comprising apatterned multilayer composition of the invention.

A 91 wt % silver composition was prepared, following the procedure asdescribed in example 1, using silver powder (22.72 g, d50/d90=870/1780),20 wt % Elvacite® 2028 (11.29 g) and di(ethylenegylcol)dibenzoate (0.042g). The final dispersion was filtered through 12 and 8μ stainless steelscreens as in example 4. The dispersion was coated using the generalprocedure entitled “Donor Preparation” on organic LTHC Green PET donorsubstrate and dried at about 45° C. for 20 min to provide a multilayerdonor.

The donor was imagined onto a Melinex® ST 504 receiver sheet using thegeneral procedures entitled “Thermal Imaging Equipment and DonorMounting”. Printing pattern was: mesh/grid pattern of 50 micron lineswith 500 micron center-to-center spacing. The printing condition was as:surface depth=70, drum speed=40 rpm and printing power=8.85 Watt.

The EMI shielding effectiveness in decibels (dB) of the example wasdetermined as outlined in ASTM D4935-99, Standard Test Method forMeasuring the Electromagnetic Shielding Effectiveness of PlanarMaterials, using a Hewlett-Packard HP8753C Vector Network Analyzer andElgal SET-19A Shielding Effectiveness Tester. The EMI effectiveness was:30-40 dB (0-2800 MHz) and 25-30 dB (2800-3000 MHz) as illustrated inFIG. 10.

FIG. 11 is a photomicrograph at 5× magnification of an EMI shieldingelement of the invention made in a similar manner to example 24.

Examples 25-30 Latex Binder Preparation for Examples 25-30

Latex binders that were used in the preparation of certain donorelements were prepared according to the procedures of WO 03/099574 withthe materials reported in Table 3. The chain transfer agent solutionused was that described on page 28 of the WO 03/099574. Compositions arereported in Table 4 and were characterized by the analytical methodsreported in the same reference. Monomers and initiators werecommercially available (Aldrich Chemical Co., Milwaukee, Wis.) and usedas received. The surfactant was Polystep® B-7, a 29 wt % solution ofammonium lauryl sulphate in water (Stepan Co).

TABLE 3 Materials for the Synthesis of Latex Resins Used in Examples25-30 Acrylic Latex Resin Reagent (grams) L-56-3 L-33-3 L-34-1Polystep ® B-7 6.90 6.90 6.90 Ammonium Persulfate 0.20 0.20 0.20 MethylMethacrylate (MMA) 252.0 228.0 236.0 Butyl Acrylate (BA) 120.0 160.0160.0 Methacrylic Acid (MAA) 12.0 12.0 4.0 Chain Transfer Agent Solution16 0 0

TABLE 4 Composition and Analytical Data for Latex Resins Used inExamples 25-30 Chain Transfer Particle Solids MMA BA MAA Agent SolutionDiameter Tg Mn/ Mw/ Latex Wt % Wt % Wt % Wt % Wt % (nm) (° C.) 1000 1000L-56-3 32.6 63 30 3 4 75 56 57 135 L-33-3 33.3 57 40 3 0 93 33 244 1399L-34-1 33.4 59 40 1 0 93 34 235 1539 MMA: Methyl Methacrylate; BA: ButylAcrylate; MAA: Methacrylic Acid.

Preparation of Dispersions for Ag Layers of Examples 25-30

The dispersions were prepared according to the procedure for dispersingsilver nanoparticles given in Example 1 with the materials reported inTable 5 with the exception that for entry 5 of Table 5, the dispersionwas filtered through 12 and 8 micron stainless steel screens (TwillDutch Weave, mesh count 200×1400 and 325×2300, absolute filter rating:12-14 and 8 microns, Sefar America Inc., Depew, N.Y.).

TABLE 5 Materials for Ag Nanoparticle Layers of Examples 25-30 MetalPowder Dispersant Additives Entry Solvent d50/d90 Wt. Dry Dry No.(g)^(a) M/wt %^(b) (nm)^(c) (g) ID Wt % wt. (g) ID^(d) wt. (g) 1 XylenesAg/89.8 220/430 22.502 Elvacite ® 20 2.501 DGD 0.057 15.006 2028^(e) 2Xylenes Ag/88.8 350/730 20.042 Elvacite ® 20 2.476 DGD 0.063 17.6012028^(e) 3 DI H₂O Ag/87.1 220/430 26.250 Joncryl ® 45 3.762 Zonyl 0.13315.427 538^(f) FSA 25 wt %^(g) 4 Xylenes Ag/88.6 350/730 10.031Elvacite ® 20 1.240 DGD/ 0.026/  8.810 2028^(e) SDA 0.027 4733 5 XylenesAg/89.9  870/1780 22.564 Elvacite ® 20 2.5002 DGD 0.046 12.501 Flake2028^(e) ^(a)DI = deionized. ^(b)Weight % of the metal in the dry film.^(c)Spherical particles were utilized unless indicated otherwise.^(d)DGD = diethylene glycol dibenzoate. ^(e)Solution in xylenes.^(f)Solution in water. ^(g)Solution in 1:1 water:isopropanol.

Example 25 PANI-CNT—Ag Nanoparticle Multi-Layer

This example illustrates the process of the invention wherein a thermalimaging substrate was fabricated with a base film; chrome LTHC layer;and polyaniline-carbon nanotube (PANI-CNT) and silver transfer layers inlayered sequence. Thermal transfer onto a receiver comprising asurface-treated base film gave a receiver element with a base film,surface treatment, and patterned silver and PANI-CNT layers in layeredsequence. Post-processing steps improved line-edge quality.

A. Preparation of PANI-CNT—Ag Nanoparticle Multi-Layer Donor Substrate

(a) Preparation and coating of polyaniline layer. A mixture of HiPco RawCNT (0.1219 g, from Carbon Nanotechnologies, Inc., Houston, Tex.),Disperbyk® 163 (0.067 g, BYK Chemie USA Inc., Wallingford, Conn.)1,2-dichlorobenzene (8.855 g) and xylenes (20.662 g) was treated in aroom temperature water bath with a sonication probe (Dukane Co. Model40TP200, Transducer Model 41C28) for 10 minutes, during which time themixture was stirred gently with a spatula at 5 minute intervals. ThenPANI-DNNSA [7.325 g, 22.23% by wt. in xylenes and 2-butoxyethanol (4:1ratio) with 0.7 acid doping, synthesized according to U.S. Pat. No.5,863,465] was added into the above mixture and the mixture was placedin a 45° C. water bath for 5 minutes. After equilibration of thetemperature, the mixture was treated with sonication for 5 minutes,during which time the mixture was stirred gently with a spatula atone-minute intervals. The resulting dispersion was filtered through 1.0micron Nitex® 03-1/1 nylon screen (mesh count 690×470, Pore size: 1micron, Sefar America Inc., Depew, N.Y.). Into the filtrate was added30.5 microliter of a 10 wt % solution in xylenes of Triton® X 114 (UnionCarbide Co, Danbury, Conn.). The dispersion (10.9 mL) was coated onto a40% T Cr PET donor substrate (˜90 by 52 cm) using a CV coater at 5.8ft/min with a CN#12 formed Buschman rod and dried at 40° C. for 25minutes.

(b) Preparation and coating of silver layer. The components of thesilver formulation and dispersion are described in entry 2 of Table 5above. The dispersion (7 mL) was coated onto the PANI-CNT layer on the40% T Cr PET donor substrate using a CV coater at 5.8 ft/min with a CN#6formed Buschman rod and dried at 48° C. for 20 minutes.

B. Thermal Transfer Process for Patterning PANI-CNT—Ag NanoparticleMulti-Layer.

A portion of the multi-layer donor (˜30 cm×20 cm) and a thermal imagingMelinex® ST 504 receiver (˜28 cm×18 cm) were loaded into the CreoTrendsetter® 800 thermal platesetter according to the proceduredescribed above. Blocks (4.75 cm×1.5 cm) of serpentine patterns wereprinted with 200, 100, and 50 micron line widths with spacing betweenthe lines equivalent to the line width. Printing parameters were asfollows: surface depth=47; surface reflectivity=0.52; escan=0. Thepatterns were printed at drum speed 120 (7.5-10.75 W in 0.25 Wincrements) and drum speed 60 (4.5-8 W in 0.25 W increments).

C. Thermal Transfer Evaluation and Post-Processing.

Transfer was incomplete at drum speed 60. Transfer was complete at drumspeed 120 but, with the exception of the 200 micron lines printed at9.25 W and above, material in non-exposed regions between the printedlines was transferred along with the lines. Contact of an adhesivesurface (Scotch® tape, 60 sec) with the 50 micron lines printed at drumspeed 120 at 9.75 W selectively removed the material between the linesto yield the desired 50 micron serpentine pattern on the receiver withclean line edges and no line breaks.

D. Electrical Characterization.

Sheet resistance was measured according to the standard procedure givenabove. Rsh of less than 1 ohm/sq was measured for lines printed at drumspeed 120 at 7.75 W and above, with Rsh measuring 0.4 ohm/sq at 10 W andabove.

Example 26 PANI-CNT—Ag Nanoparticle—Dielectric Multi-Layer

This example illustrates the process of the invention wherein a thermalimaging substrate was fabricated with a base film; chrome LTHC layer;and PANI-CNT, silver, and dielectric transfer layers in layeredsequence. Thermal transfer onto a receiver comprising a surface-treatedbase film gave a receiver element with a base film, surface treatment,and patterned dielectric, silver and PANI-CNT layers in layeredsequence. Thermal transfer onto a receiver comprising a surface-treatedbase film with a patterned PANI-CNT layer gave a receiver element with abase film, surface treatment, and patterned PANI-CNT, dielectric, silverand PANI-CNT layers in layered sequence. Post-processing steps improvedline-edge quality.

A. Preparation of Multilayer PANI-CNT—Ag Nanoparticle—Dielectric DonorSubstrate

(a) Preparation and coating of polyaniline layer. Procedure wasidentical to that described above in Example 25-A-a.

(b) Preparation and coating of silver layer. The components of thesilver formulation and dispersion are described in entry 3 of Table 5above. The dispersion (5 mL) was coated onto the PANI-CNT layer on the40% T Cr PET donor substrate (˜90 by 52 cm) using a CV coater at 5.8ft/min with a CN#7 formed Buschman rod and dried at 49° C. for 20minutes. (c) Preparation and coating of dielectric layer. Generalaqueous dielectric layer formulation procedure was followed using 16.76g of Joncryl® 63 (30 wt %), 16.78 g of Joncryl® 95 (30 wt %), 0.21 g ofSDA 2860, 0.50 g of Byk® 348 (10 wt % in water), and 23.26 g of water togive a formulation with a pH of 8.51. The resulting solution (3 mL) wascoated onto the silver nanoparticle layer with a CN#2 formed Buschmanrod at 6.3 ft/min with a CV coater and dried at 45° C. for 6 minutes.The wt % of materials in the dried coating was as follows: 48.7 wt %Joncryl® 63, 48.8 wt % Joncryl® 95, 2.0 wt % SDA 2860, and 0.50 wt %Byk® 348. [Joncryl® 63 is a solution of a water-soluble styrene acrylicresin with a pH of 8.4, MW of 12,000, acid number of 213 and Tg of 73.Joncryl® 95 is an emulsion of an ammonia salt of modified styreneacrylic polymers with a pH of 8.0 and an acid number of 70. Both arefrom Johnson Polymer.]

B. Preparation of a Thermal Imaging Receiver with a Patterned PANI-CNTLayer

(a) Preparation and coating of PANI-CNT donor substrate. Procedure andmaterials for the dispersion were identical to those of Example 25-A-aexcept that xylenes was used as the solvent instead of thexylenes/1,2-dichlorobenzene mixture. The amounts of materials utilizedwere as follows: 0.1230 g of HiPco Raw CNT, 0.063 g of Disperbyk® 163,29.680 g of xylenes, 5.144 g of PANI-DNNSA [31.68% by wt. in xylenes and2-butoxyethanol (4:1 ratio) with 0.7 acid doping], and 28.9 micro-L ofTriton®X 114 (10 wt % in xylenes). The dispersion (10.9 mL) was coatedonto a 40% T Cr PET donor substrate (˜90 cm×52 cm) using a CV coater at5.8 ft/min with CN#10 formed Buschman rod and dried at 45° C. for 20minutes.

(b) Thermal transfer process for patterning PANI-CNT layer on base filmof receiver. A portion of the PANI-CNT donor (˜30 cm×20 cm; dried for anadditional 60 min at 50° C. five months prior to the thermal transferexperiment) and a thermal imaging Melinex® ST 504 receiver (˜28 cm×18cm) were loaded into the Creo Trendsetter® 800 thermal platesetteraccording to the general procedure described above. Two rectangularpatterns (1.25 cm×0.75 cm), one a solid block of material (hereinreferred to as the solid-block pattern) and one in which the materialwas patterned into vertical lines of 120 microns in width with spacingof 240 microns (herein referred to as the vertical-line pattern), wereutilized as the patterns in this printing experiment. Two rows (rows 1and 2) were printed with thirteen alternating solid-block andvertical-line patterns in each line. Printing parameters were asfollows: drum speed=160; surface depth=47; surface reflectivity=0.46;escan=0; power=5.75 W (row 1) and 5.45 W (row 2).

C. Thermal Transfer Process for Patterning PANI-CNT—AgNanoparticle—Dielectric Multi-Layer.

The PANI-CNT donor was removed from the drum while leaving the patternedreceiver in place on the drum. A portion of the multi-layer donor (˜30cm×20 cm) was loaded into the Creo Trendsetter® 800 thermal platesetteraccording to the general procedure described above. Printing parametersfor all rows were as follows: surface depth=47; surfacereflectivity=0.54; escan=0; alternating solid-block and vertical linepatterns. Row 1: Multi-layer printed on top of the patterned PANI-CNTlayer at drum speed 120 from 7.50 to 10.50 W in 0.25 W increments. Row2: Multi-layer printed on top of the patterned PANI-CNT layer at drumspeed 160 from 9.00 to 12.00 W in 0.25 W increments. Row 3: Multi-layerprinted onto the receiver surface at drum speed 160 from 7.50 to 10.50 Win 0.25 W increments.

D. Thermal Transfer Evaluation and Post-Processing.

The multilayer transferred to varying extents at all powers with optimalquality and highest degree of transfer observed at 7.5-8.25 W for Row 1,9.25-10 W for Row 2, and 8-8.25 W for Row 3. In all three rows, materialin non-exposed regions between the printed lines was transferred alongwith the lines. The material that was transferred between the lines wasvery loosely adhered to the receiver and to the lines themselves andcould be easily and selectively removed by contact with an adhesivesurface, leaving the desired line pattern on the receiver. This wasexemplified in Row 1 (10.5 W), Row 2 (12.0 W) and Row 3 (10.5 W) using atacky roller and in Row 3 (10.25 W) using Scotch® tape (1 min contact).

Example 27 Black—Ag Nanoparticle—Dielectric Multi-Layer

This example illustrates the process of the invention wherein a thermalimaging substrate was fabricated with a base film; chrome LTHC layer;and black, silver, and dielectric transfer layers in layered sequence.Thermal transfer onto a receiver comprising a surface-treated base filmgave a receiver element with a base film, surface treatment, andpatterned dielectric, silver and black layers in layered sequence.Thermal transfer onto a receiver comprising a surface-treated base filmwith a patterned PANI-CNT layer gave a receiver element with a basefilm, surface treatment and patterned PANI-CNT, dielectric, silver andblack layers in layered sequence. Thermal transfer onto a receivercomprising a surface-treated base film with a patterned silvernanoparticle layer gave a receiver element with a base film, surfacetreatment and patterned silver, dielectric, silver and black layers inlayered sequence. Post-processing steps improved line-edge quality.

A. Preparation of Multilayer Black—Ag Nanoparticle—Dielectric DonorSubstrate

(a) Preparation and coating of black layer. General aqueous transferlayer formulation procedure was followed using 12.60 g of Joncryl® 56(27 wt %), 4.93 g of Latex L-34-1 (30 wt %), 0.025 g of SDA 2860, 0.050g of Byk® 348, 0.910 g of Carbon Black Acroverse Paste 32B56 (33 wt %;Penn Color), and 11.60 g of water to give a formulation with a pH of9.20. The resulting solution (3 mL) was coated onto the 40% T Cr BluePET donor substrate (˜90 by 52 cm) using a CV coater with a CN#2 formedBuschman rod at 6.3 ft/min and dried at 45° C. for 6 minutes. The wt %of materials in the dried coating was as follows: 63.0 wt % Joncryl® 56,30.1 wt % Latex L-34-1, 0.5 wt % SDA 2860, 0.90 wt % Byk® 348, and 5.6wt % 32B56 Carbon Black. [Joncryl® 56 is a solution of a water-solublestyrene acrylic resin with a pH of 9.1, MW of 4,600, acid number of 108and Tg of 60 from Johnson Polymer.]

(b) Preparation and coating of silver layer. The components of thesilver formulation and dispersion are described in entry 1 in Table 5above. The dispersion (7 mL) was coated onto the black layer on the 40%T Cr Blue PET donor substrate using a CV coater at 5.8 ft/min with aCN#6 formed Buschman rod and dried at 48° C. for 20 min and later for 60min at 50° C.

(c) Preparation and coating of dielectric layer. Formulation and coatingprocess were identical to that of Example 26-A-c. The donor was driedfor an additional 45 min at 45° C. immediately prior to the thermaltransfer experiment.

B. Preparation of a Thermal Imaging Receiver with a Patterned PANI-CNTLayer in Rows 1 and 2 and a Patterned Silver Nanoparticle Layer in Row 3

(a) Preparation and coating of PANI-CNT donor substrate. Formulation andcoating were identical to that of Example 26-B-a.

(b) Thermal transfer process for patterning PANI-CNT layer on base filmof receiver. Process was identical to that of Example 26-B-b with thefollowing exceptions: surface reflectivity=0.54; power=5.5 W (Rows 1 &2), fourteen alternating patterns were printed in Row 2.

(c) Preparation and coating of silver nanoparticle donor substrate. Thecomponents of the silver formulation and dispersion are described inentry 4 in Table 5 above. The dispersion (8 mL) was coated onto Melinex®453 donor film (˜90 by 52 cm) using a CV coater at 5.8 ft/min with aCN#6 formed Buschman rod and dried at 47° C. for 20 min. The donor wasdried for an additional 60 min at 50° C. approximately three weeks priorto the thermal transfer experiment.

(d) Thermal transfer process for patterning silver nanoparticle layer onbase film of receiver. The PANI-CNT donor was removed from the drumwhile leaving the patterned receiver in place on the drum. A portion ofthe silver nanoparticle donor (˜30 cm×20 cm) was loaded into the CreoTrendsetter® 800 thermal platesetter according to the general proceduredescribed above. Fourteen alternating solid-block patterns andvertical-line patterns (1.25×0.75 cm) were printed in Row 3. Printingparameters were as follows: drum speed=40; surface depth=30; surfacereflectivity=0.48; escan=0; power=4.8 W.

C. Thermal Transfer Process for Patterning Black—AgNanoparticle—Dielectric Multi-Layer.

The silver nanoparticle donor was removed from the drum while leavingthe patterned receiver in place on the drum. A portion of themulti-layer donor (˜30 cm×20 cm) was loaded into the Creo Trendsetter®800 thermal platesetter according to the general procedure describedabove. Printing parameters for all rows were as follows: surfacedepth=60; surface reflectivity=0.30; escan=0; alternating solid-blockand vertical line patterns (1.25×0.75 cm). Row 1: Multi-layer wasprinted directly on top of the patterned PANI-CNT layer at drum speed 40from 4.00 to 7.25 W in 0.25 W increments. Row 2: Multi-layer was printedon top of and slightly offset from the patterned PANI-CNT layer at drumspeed 100 from 6.00 to 9.25 W in 0.25 W increments. Row 3: Multi-layerwas printed on top of the patterned silver nanoparticle layer at drumspeed 40 from 3.50 to 7.40 W in 0.30 W increments. Row 4: Multi-layerwas printed onto the receiver surface at drum speed 40 from 3.50 to 7.40W in 0.30 W increments.

D. Thermal Transfer Evaluation and Post-Processing.

Complete transfer of the multilayer was observed at 4.5 W for Row 1, at3.75-4.75 W for Row 3 and at 3.5-4.5 W for Row 4. For Row 2, the offsetmultilayer transferred to varying extents at the different powers ontoboth the patterned PANI-CNT layer and onto the receiver. In all fourrows, some material in non-exposed regions between the printed lines wastransferred along with the lines. For Rows 3 and 4, the material thatwas transferred between the lines could be easily and selectivelyremoved by contact with an adhesive surface, leaving the desired linepattern on the receiver. This was exemplified in Row 3 (4.75 W) and Row4 (3.75 W) with Scotch® tape (30-60 sec contact).

Example 28 Black—Dielectric—Ag Nanoparticle Multi-Layer

This example illustrates the process of the invention wherein a thermalimaging substrate was fabricated with a base film; organic LTHC layer;and black, dielectric and silver transfer layers in layered sequence.Thermal transfer onto a receiver comprising a surface-treated base filmgave a receiver element with a base film, surface treatment, andpatterned silver, dielectric, and black layers in layered sequence.Thermal transfer onto a receiver comprising a surface-treated base filmwith a patterned dielectric layer gave a receiver element with a basefilm, surface treatment, and patterned dielectric, silver, dielectric,and black layers in layered sequence.

A. Preparation of Multilayer Black—Dielectric—Ag Nanoparticlemulti-layer donor substrate

(a) Preparation and coating of black layer. General aqueous black layerformulation procedure was followed using 11.10 g of Joncryl® 56 (27 wt%), 0.135 g of ammonium hydroxide (3 wt % in water), 0.060 g of SDA2860, 0.20 g of Byk® 348 (10 wt % in water), 3.110 g of Carbon BlackAcroverse Paste 32B56 (33 wt %; Penn Color), and 8.28 g of water to givea formulation with a pH of 9.34. The resulting solution (3 mL) wascoated onto an Organic LTHC Green PET donor substrate (˜90 by 52 cm)using a CV coater with a CN#2 formed Buschman rod at 6.3 ft/min anddried at 45° C. for 6 minutes. The wt % of materials in the driedcoating was as follows: 73.0 wt % Joncryl® 56, 0.1 wt % AmmoniumHydroxide, 1.5 wt % SDA 2860, 0.50 wt % Byk® 348, and 25.0 wt % 32B56Carbon Black.

(b) Preparation and coating of dielectric layer. Formulation and coatingprocess were identical to that of Example 26-A-c.

(c) Preparation and coating of silver layer. Formulation and coatingprocess were identical to that of Example 27-A-b.

B. Preparation of a Thermal Imaging Receiver with a Patterned DielectricLayer in Rows 1, 2, 5 and 6.

(a) Preparation and coating of dielectric donor substrate. Generalaqueous dielectric layer formulation procedure was followed using 33.32g of Latex L-56-3 (30 wt %), 12.34 g of Latex L-33-3 (30 wt %), 0.87 gof SDA 2860, 0.165 g of Byk® 345, 4.164 g of 2-butoxyethanol, and 38.85g of water to give a formulation with a pH of 3.84. The resultingsolution (7 mL) was coated onto the Organic LTHC Green PET donorsubstrate (˜90 by 52 cm) with a CN#7 formed Buschman rod with a CVcoater at 9.8 ft/min and dried at 45° C. for 6 minutes. The wt % ofmaterials in the dried coating was as follows: 68.3 wt % Latex L-56-3,25.3 wt % Latex L-33-3, 5.4 wt % SDA 2860, and 1.0 wt % Byk® 345.

(b) Thermal transfer process for patterning dielectric layer on basefilm of receiver. A portion of the dielectric donor (˜30 cm×20 cm) and athermal imaging Melinex® ST 504 receiver (˜28 cm×18 cm) were loaded intothe Creo Trendsetter® 800 thermal platesetter according to the generalprocedure described above. Seventeen solid-block patterns were printedin Rows 1 and 5 and seventeen vertical-line patterns were printed inRows 2 and 6. Printing parameters were as follows: drum speed=160;surface depth=70; surface reflectivity=0.30; escan=0; power=9.70 W (rows1 and 5) and 10.30 W (rows 2 and 6). Patterns were 1.9×1.3 cm.

C. Thermal Transfer Process for Patterning Black—Dielectric—AgNanoparticle Multi-Layer.

The dielectric donor was removed from the drum while leaving thepatterned receiver in place on the drum. A portion of the multi-layerdonor (˜30 cm×20 cm) was loaded into the Creo Trendsetter® 800 thermalplatesetter according to the general procedure described above. Printingparameters for all rows were as follows: surface depth=70; surfacereflectivity=0.24; escan=0; drum speed=60. Row 1: The multi-layer wasprinted in solid-block patterns on top of the patterned dielectric layerfrom 4.50 to 9.30 W in 0.30 W increments. Row 2: The multi-layer wasprinted in vertical-line patterns on top of the patterned dielectriclayer from 5.20 to 10.00 W in 0.30 W increments. Row 3: The multi-layerwas printed in alternating vertical-line and solid-block patterns ontothe receiver from 5.20 to 10.80 W in 0.40 W increments. Patterns were1.9×1.3 cm for Rows 1 and 2 and 1.9×0.8 cm for Row 3.

D. Evaluation of Thermal Transfer of Multi-Layer.

Complete transfer of the Ag portion of the multilayer donor wasexhibited in exposed regions along with complete transfer of thedielectric and black portions of the multilayer, except at some swathboundaries and coating defects, at 4.5-7.5 W for Row 1, at 5.2-10.0 Wfor Row 2, and at 5.2-6.7 W for Row 3 with the best line-edge qualityfor Row 3 observed at 5.2-5.8 W.

Example 29 Dielectric—Ag Nanoparticle Bi-Layer

This example illustrates the process of the invention wherein a thermalimaging substrate was fabricated with a base film; chrome LTHC layer;and dielectric and silver transfer layers in layered sequence. Thermaltransfer onto a receiver comprising a surface-treated base film gave areceiver element with a base film, surface treatment and patternedsilver and dielectric layers in layered sequence. Thermal transfer ontoa receiver with a surface-treated base film with a patterned dielectriclayer gave a receiver element with a base film, surface treatment andpatterned dielectric, silver, and dielectric layers in layered sequence.Selective removal from the receiver of the patterned dielectric layeronly of the patterned bi-layer and also of both layers of the patternedbi-layer was achieved in post-processing steps by tuning transferconditions. These steps illustrate selective removal of a carrier layerand also transfer of a printed pattern from the receiver to anothersurface.

A. Preparation of Dielectric—Ag Nanoparticle Bi-Layer Donor Substrate

(a) Preparation and coating of dielectric layer. Formulation wasidentical to that of Example 28-B-a. The resulting solution (3 mL) wascoated onto the 40% T Cr Blue PET donor substrate (˜90 by 52 cm) with aCN#2 formed Buschman rod with a CV coater at 9.8 ft/min and dried at 45°C. for 6 minutes.

(b) Preparation and coating of silver layer. Formulation and coatingprocess were identical to that of Example 27-A-b.

B. Preparation of a Thermal Imaging Receiver with a Patterned DielectricLayer in Rows 1, 2, 5 and 6.

Rows 4, 5 and 6 of the thermal imaging receiver prepared in Example 28,referred to herein as Receiver A, were utilized and are referred to inthe present example as Rows A4, A5 and A6. A separate, non-patternedST504 Melinex® receiver, referred to herein as Receiver B, was alsoutilized (Rows B1, B2, B3 and B4).

C. Thermal Transfer Process for Patterning Dielectric—Ag NanoparticleBi-Layer.

The multilayer donor of Example 28 was removed from the drum whileleaving the patterned Receiver A in place on the drum. A portion of thedielectric-Ag nanoparticle bi-layer donor of the present example (˜30cm×20 cm) was loaded into the Creo Trendsetter® 800 thermal platesetteraccording to the general procedure described above. Printing parametersfor all rows of both receivers were as follows: surface depth=70;surface reflectivity=0.24; escan=0. Following the printing of rows A4,A5 and A6, the bi-layer donor was peeled off of Receiver A, and ReceiverA was then removed from the drum. Next, Receiver B and the bi-layerdonor were loaded into the Creo Trendsetter® 800 thermal platesetteraccording to the general procedure. Rows B1, B2, B3 and B4 were printed.The bi-layer was printed onto a receiver surface in Row A4 (alternatingvertical-line and solid-block patterns; 4.50 to 10.10 W in 0.40 Wincrements; drum speed 60), Row B1 (vertical-line patterns; 6.00 to10.50 W in 0.25 W increments; drum speed 120), Row B2 (solid-blockpatterns; 5.00 to 9.50 W in 0.25 W increments; drum speed 120), Row B3(vertical-line patterns; 8.00 to 12.50 W in 0.25 W increments; drumspeed 160), and Row B4 (solid-block patterns; 7.00 to 11.50 W in 0.25 Wincrements; drum speed 160). The bi-layer was printed onto the patterneddielectric layer in Row A5 (solid block patterns; 4.50 to 9.30 W in 0.30W increments; drum speed 60) and Row A6 (vertical-line patterns; 5.00 to9.80 W in 0.30 W increments; drum speed 60). Patterns were 1.9×0.8 cmfor Row A4, 1.9×1.3 cm for Rows A5 and A6, and 1.3×1.0 cm for Rows B1,B2, B3 and B4.

D. Thermal Transfer Evaluation and Post-Processing.

Bi-layer transferred at all powers with complete and highest quality oftransfer observed at 4.5-4.9 W for Row A4; at 4.5 W for Row A5; at5.3-5.6 W for Row A6 with good line-edge quality; at 6.5 W and above forRow B1 with optimal transfer with straight line edges at 7.25 W; at 8.25W and above for Row B2; at 8.75-9 W and at 12-12.5 W for Row B3; and at10.25 W and above for Row B4. Contact with an adhesive surface (Scotch®tape, 30 sec) selectively removed the dielectric layer only of thebi-layer, leaving the Ag lines on the receiver, for the vertical linepattern of 7.7 W of Row A4. Contact with an adhesive surface (Scotch®tape, 60 sec) selectively removed both layers of the bi-layer from thereceiver and transferred the pattern to the surface of the tape for the8.25 W patterns of Row B2 (greater than 90% removal) and Row B4 (greaterthan 95% removal).

Example 30 Ag Nanoparticle—Dielectric Multi-Layer

This example illustrates the process of the invention wherein a thermalimaging substrate was fabricated comprising a base film; organic LTHClayer; and silver and dielectric transfer layers in layered sequence.Thermal transfer to a receiver comprising a surface-treated base filmgave a receiver element with a base film, surface treatment andpatterned dielectric and silver transfer layers in layered sequence.Post-processing steps improved line-edge quality.

A. Preparation of Ag Nanoparticle—Dielectric Multi-Layer Donor Substrate

(a) Preparation and coating of silver layer. The components of thesilver formulation and dispersion are described in entry 5 of Table 5above. The dispersion (14 mL) was coated onto an Organic LTHC Green PETdonor substrate (˜90 by 52 cm) using a CV coater at 5.8 ft/min with aCN#10 formed Buschman rod and dried at 47° C. for 20 minutes to give afilm with a thickness of 2.9 microns.

(b) Preparation and coating of dielectric layer. Formulation and coatingwere identical to that of Example 26-A-c. The donor was dried for anadditional 60 min at 50° C. immediately prior to the thermal transferexperiment.

B. Thermal Transfer Process for Patterning Ag Nanoparticle—DielectricMulti-Layer.

A portion of the multi-layer donor (˜30×20 cm) and a thermal imagingMelinex® ST 504 receiver (˜28 cm×18 cm) were loaded into the CreoTrendsetter® 800 thermal platesetter according to the proceduredescribed above. Blocks of serpentine patterns were printed with 200,100, and 50 micron line widths with spacing between the lines equivalentto the line width. Printing parameters were as follows: surfacedepth=70; surface reflectivity=0.3; escan=0. The patterns were printedat drum speed 120 (8.5-12 W in 0.25 W increments), drum speed 60 (5.5-9W in 0.25 W increments), and drum speed 40 (5-8.5 W in 0.25 Wincrements).

C. Thermal Transfer Evaluation and Post-Processing.

Transfer was complete at all drum speeds and powers with the exceptionof drum speed 120 at 8.5-9. 25 W. For the 100 and, particularly, 50micron lines, material in non-exposed regions between the printed lineswas transferred along with the lines. Contact with an adhesive surface(Scotch tape, 60 sec) selectively removed the material between the 50micron serpentine lines that were printed with drum speed 40 at 8.25 Wto yield the desired pattern on the receiver with clean line edges andno line breaks.

Example 31 Printed Touchpad Component Utilizing PatternedAg-Nanoparticle Layers

This example illustrates the preparation of a touchpad componentcomprising a multi-layer composition of the invention.

A. Preparation and Coating of Silver Layer.

The silver formulation and dispersion were prepared as described inExample 1. The dispersion (7 mL) was coated onto a 40% T Cr PET donorsubstrate (˜90 by 52 cm) using a CV coater at 5.8 ft/min with a CN#6formed Buschman rod and dried at 47° C. for 20 minutes. Two days later,the coating was further dried for ˜1 h at 50° C.

B. Thermal Transfer Process for Patterning Ag Nanoparticle Layer.

A portion of the donor (˜30 cm×20 cm) and Melinex® ST504 receiver (˜28cm×18 cm) was loaded into the Creo Trendsetter® 800 thermal platesetteraccording to the general procedure described above. Printing parameterswere as follows: surface depth=65; surface reflectivity=0.65; escan=0.Two blocks (˜9 cm×16 cm) consisting of a standard touchpad pattern ofspiraling, rectangular parallel lines of 10 micron width with 2.1 mmspacing were printed at drum speed 160 at 11.65 W. Larger alignmentcrossbars and pads were printed at the four corners of each 9×16 blockat drumspeed 170 at 8.40 W.

C. Evaluation of Thermal Transfer of Multi-Layer.

Transfer of both the lines and crossbars and pads was essentiallycomplete and of good quality with straight line edges.

D. Construction of the Touchpad Component.

Each of the two printed 9×16 cm touchpad patterns was cut from thereceiver. A sheet of 8142 optically clear adhesive (3M) was trimmed tomatch the size of the printed 9×16 cm touchpad patterns. The adhesivecover sheets were removed as it was attached to the backside (sideopposite the silver pattern) of one of the printed touchpad patterns andthe front side (side containing the silver pattern) of the other printedtouchpad pattern, using the crossbars and pads to visually align the twopatterns. The result was a touchpad component containing a base film,patterned silver lines, adhesive, base film and patterned silver linesin layered sequence. The UV-VIS transmission of the touchpad componentwas measured in an area with the silver pattern and in an area withoutthe silver pattern. Transmission from 500-1100 nm was 87% for thepatterned area and 89% for the non-patterned area.

1. A metal composition comprising: a) about 85 to about 95 wt %, basedon the total weight of the metal composition, of a metal powder selectedfrom the group consisting of: Ag, Cu and alloys thereof; comprising aplurality of metal particles having an average longest dimension ofabout 5 nm to about 1500 nm; b) about 5 to about 35 wt % of a dispersantcomprising one or more resins selected from the group consisting of:nonconducting polymers selected from the group consisting of: acrylicand styrenic-acrylic latexes, and solution-based acrylics andstyrenic-acrylic (co)polymers, and combinations thereof; copolymers ofethylene with one or more monomers selected from the group consistingof: (meth)acrylate(s), vinyl acetate, carbon monoxide and (meth)acrylicacid; and polyvinylacetate and its copolymers; and c) a near infrareddye selected from the group consisting of indocyanines, phthalocyanines,and merocyanines.
 2. The metal composition of claim 1, furthercomprising up to about 10 wt %, based on the total weight of dispersant,of one or more additive(s) selected from the group consisting of:pigments, dyes, and conducting particles with an average longestdimension of about 5 nm to about 1500 nm, said conducting particlesselected from the group consisting of: carbon black, carbon nanotubes,Au, Pd, and alloys of Au and Pd.
 3. The metal composition of claim 1,comprising Ag powder with an average particle size of about 100 nm toabout 400 nm.
 4. The metal composition of claim 1, wherein thedispersant comprises resins selected from the group consisting of:acrylic and styrenic-acrylic latexes, and solution-based acrylics andstyrenic-acrylic (co)polymers, and combinations thereof.
 5. A multilayerthermal imaging donor comprising: a base film, a metal transfer layer,and a LTHC layer interposed between said base film and said metaltransfer layer; wherein said metal transfer layer has thickness of about0.2 to about 3 microns and comprises a metal composition (A) comprisingabout 85 to about 95 wt % of a metal powder selected from the groupconsisting of: Ag, Cu and alloys thereof; comprising a plurality ofmetal particles characterized by an average longest dimension of about 5nm to about 1500 nm; and about 5 to about 35 wt % of a dispersantcomprising one or more resins selected from the group consisting of:nonconducting polymers selected from the group consisting of: acrylicand styrenic-acrylic latexes and solution-based acrylic andstyrenic-acrylic (co)polymers; and combinations thereof; copolymers ofethylene with one or more monomers selected from the group consistingof: (meth)acrylate(s), vinyl acetate, carbon monoxide and (meth)acrylicacid; and polyvinylacetate and its copolymers.
 6. The donor of claim 5,wherein the metal transfer layer consists essentially of the metalcomposition (A).
 7. The donor of claim 5, wherein the metal composition(A) further comprises up to about 10 wt %, based on the total weight ofdispersant, of one or more additives selected from the group of:pigments, dyes, and conducting particles with an average longestdimension of about 5 nm to about 1500 nm, selected from the groupconsisting of: carbon black, carbon nanotubes, Au, Pd, and alloys of Auand Pd.
 8. The donor of claim 5, wherein said metal composition (A)comprises Ag powder with an average particle size of about 100 nm toabout 400 nm.
 9. The donor of claim 5, wherein the dispersant comprisesresins selected from the group consisting of: acrylic andstyrenic-acrylic latexes, and solution-based acrylics andstyrenic-acrylic (co)polymers, and combinations thereof.
 10. The donorof claim 5, wherein the base film comprises a polymeric materialselected from the group consisting of: polyethylene terephthalate,polyethylene naphthalate, triacetyl cellulose and polyimide.
 11. Thedonor of claim 5 wherein the LTHC layer comprises one or more radiationabsorbers selected from the group consisting of: metal films selectedfrom Cr and Ni; carbon black; graphite; and near infrared dyes with anabsorption maxima in the range of about 600 to 1200 nm within the LTHClayer.
 12. The donor of claim 11 wherein the LTHC layer is a metal filmcomprising Cr or Ni.
 13. The donor of claim 5 wherein the LTHC layercomprises: one or more water-soluble or water-dispersibleradiation-absorbing cyanine compound(s) selected from the groupconsisting of: indocyanines, phthalocyanines, and merocyanines; and oneor more water-soluble or water-dispersible polymeric binders selectedfrom the group consisting of: acrylic resins, hydrophilic polyesters,sulphonated polyesters and maleic anhydride homopolymers and copolymers.14. The donor of claim 5 further comprising one or more additionaltransfer layer(s).
 15. The donor of claim 14 wherein the one or moreadditional transfer layer(s) comprises a conducting polymer selectedfrom the group consisting of: polyaniline, polythiophene, polypyrrole,polyheteroaromatic vinylenes, and their derivatives.
 16. The donor ofclaim 14 wherein the one or more additional transfer layer(s) comprisesabout 1 to about 90 wt % carbon black.
 17. A patterned multilayercomposition comprising: a) one or more base film(s); and b) one or morepatterned metal layer(s); wherein the patterned metal layer(s) has apattern comprising at least one line of width of about 1 millimeter orless, and comprises about 85 to about 95 wt % of a metal powder selectedfrom the group consisting of: Ag, Cu and alloys thereof; comprising aplurality of metal particles characterized by an average longestdimension of about 5 nm to about 1500; and about 5 to about 35 wt % of adispersant comprising one or more resins selected from the groupconsisting of: nonconducting polymers selected from the group consistingof: acrylic and styrenic-acrylic latexes and solution-based acrylic andstyrenic-acrylic (co)polymers; and combinations thereof; copolymers ofethylene with one or more monomers selected from the group consistingof: (meth)acrylate(s), vinyl acetate, carbon monoxide and (meth)acrylicacid; and polyvinylacetate and its copolymers.
 18. The patternedmultilayer composition of claim 17 wherein the base film is selectedfrom the group consisting of: polyethylene terephthalate, polyethylenenaphthalate, triacetyl cellulose, glass and polyimide.
 19. The patternedmultilayer composition of claim 17, wherein said patterned metal layeris characterized by a resistivity of about 10⁻⁴ ohm-cm or less.
 20. Thepatterned multilayer composition of claim 17 wherein said patternedmetal layer has a pattern with at least one line of width of about 10microns or less.
 21. The patterned multilayer composition of claim 17further comprising one or more additional patterned layer(s).
 22. Thepatterned multilayer composition of claim 17 wherein the one or moreadditional patterned layer(s) comprises a conducting polymer selectedfrom the group consisting of: polyaniline, polythiophene, polypyrrole,polyheteroaromatic vinylenes, and their derivatives.
 23. Anelectromagnetic interference shield comprising the patterned multilayercomposition of claim
 17. 24. The electromagnetic interference shield ofclaim 23, further comprising an additional patterned layer above orbelow the patterned metal layer.
 25. The electromagnetic interferenceshield of claim 24, wherein the additional patterned layer comprisesabout 1 to about 90 wt % carbon black.
 26. The electromagneticinterference shield of claim 23, wherein said base film is selected fromthe group consisting of: polyethylene terephthalate, polyethylenenaphthalate, triacetyl cellulose and glass; and further comprises anantireflective coating on the base film opposite the patterned metallayer.
 27. A touchpad sensor comprising a multilayer composition ofclaim
 17. 28. The touchpad sensor of claim 27 further comprising adielectric layer.
 29. The touchpad sensor of claim 28 comprising a firstbase film with a first patterned metal layer; a second base film with asecond patterned metal layer; and the dielectric layer disposed betweenthe first and second patterned metal layers.
 30. The touchpad sensor ofclaim 27 comprising a first base film, having two opposing surfaces, apatterned metal layer disposed on each of the two opposing surfaces.